1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
1095
1096
1097
1098
1099
1100
1101
1102
1103
1104
1105
1106
1107
1108
1109
1110
1111
1112
1113
1114
1115
1116
1117
1118
1119
1120
1121
1122
1123
1124
1125
1126
1127
1128
1129
1130
1131
1132
1133
1134
1135
1136
1137
1138
1139
1140
1141
1142
1143
1144
1145
1146
1147
1148
1149
1150
1151
1152
1153
1154
1155
1156
1157
1158
1159
1160
1161
1162
1163
1164
1165
1166
1167
1168
1169
1170
1171
1172
1173
1174
1175
1176
1177
1178
1179
1180
1181
1182
1183
1184
1185
1186
1187
1188
1189
1190
1191
1192
1193
1194
1195
1196
1197
1198
1199
1200
1201
1202
1203
1204
1205
1206
1207
1208
1209
1210
1211
1212
1213
1214
1215
1216
1217
1218
1219
1220
1221
1222
1223
1224
1225
1226
1227
1228
1229
1230
1231
1232
1233
1234
1235
1236
1237
1238
1239
1240
1241
1242
1243
1244
1245
1246
1247
1248
1249
1250
1251
1252
1253
1254
1255
1256
1257
1258
1259
1260
1261
1262
1263
1264
1265
1266
1267
1268
1269
1270
1271
1272
1273
1274
1275
1276
1277
1278
1279
1280
1281
1282
1283
1284
1285
1286
1287
1288
1289
1290
1291
1292
1293
1294
1295
1296
1297
1298
1299
1300
1301
1302
1303
1304
1305
1306
1307
1308
1309
1310
1311
1312
1313
1314
1315
1316
1317
1318
1319
1320
1321
1322
1323
1324
1325
1326
1327
1328
1329
1330
1331
1332
1333
1334
1335
1336
1337
1338
1339
1340
1341
1342
1343
1344
1345
1346
1347
1348
1349
1350
1351
1352
1353
1354
1355
1356
1357
1358
1359
1360
1361
1362
1363
1364
1365
1366
1367
1368
1369
1370
1371
1372
1373
1374
1375
1376
1377
1378
1379
1380
1381
1382
1383
1384
1385
1386
1387
1388
1389
1390
1391
1392
1393
1394
1395
1396
1397
1398
1399
1400
1401
1402
1403
1404
1405
1406
1407
1408
1409
1410
1411
1412
1413
1414
1415
1416
1417
1418
1419
1420
1421
1422
1423
1424
1425
1426
1427
1428
1429
1430
1431
1432
1433
1434
1435
1436
1437
1438
1439
1440
1441
1442
1443
1444
1445
1446
1447
1448
1449
1450
1451
1452
1453
1454
1455
1456
1457
1458
1459
1460
1461
1462
1463
1464
1465
1466
1467
1468
1469
1470
1471
1472
1473
1474
1475
1476
1477
1478
1479
1480
1481
1482
1483
1484
1485
1486
1487
1488
1489
1490
1491
1492
1493
1494
1495
1496
1497
1498
1499
1500
1501
1502
1503
1504
1505
1506
1507
1508
1509
1510
1511
1512
1513
1514
1515
1516
1517
1518
1519
1520
1521
1522
1523
1524
1525
1526
1527
1528
1529
1530
1531
1532
1533
1534
1535
1536
1537
1538
1539
1540
1541
1542
1543
1544
1545
1546
1547
1548
1549
1550
1551
1552
1553
1554
1555
1556
1557
1558
1559
1560
1561
1562
1563
1564
1565
1566
1567
1568
1569
1570
1571
1572
1573
1574
1575
1576
1577
1578
1579
1580
1581
1582
1583
1584
1585
1586
1587
1588
1589
1590
1591
1592
1593
1594
1595
1596
1597
1598
1599
1600
1601
1602
1603
1604
1605
1606
1607
1608
1609
1610
1611
1612
1613
1614
1615
1616
1617
1618
1619
1620
1621
1622
1623
1624
1625
1626
1627
1628
1629
1630
1631
1632
1633
1634
1635
1636
1637
1638
1639
1640
1641
1642
1643
1644
1645
1646
1647
1648
1649
1650
1651
1652
1653
1654
1655
1656
1657
1658
1659
1660
1661
1662
1663
1664
1665
1666
1667
1668
1669
1670
1671
1672
1673
1674
1675
1676
1677
1678
1679
1680
1681
1682
1683
1684
1685
1686
1687
1688
1689
1690
1691
1692
1693
1694
1695
1696
1697
1698
1699
1700
1701
1702
1703
1704
1705
1706
1707
1708
1709
1710
1711
1712
1713
1714
1715
1716
1717
1718
1719
1720
1721
1722
1723
1724
1725
1726
1727
1728
1729
1730
1731
1732
1733
1734
1735
1736
1737
1738
1739
1740
1741
1742
1743
1744
1745
1746
1747
1748
1749
1750
1751
1752
1753
1754
1755
1756
1757
1758
1759
1760
1761
1762
1763
1764
1765
1766
1767
1768
1769
1770
1771
1772
1773
1774
1775
1776
1777
1778
1779
1780
1781
1782
1783
1784
1785
1786
1787
1788
1789
1790
1791
1792
1793
1794
1795
1796
1797
1798
1799
1800
1801
1802
1803
1804
1805
1806
1807
1808
1809
1810
1811
1812
1813
1814
1815
1816
1817
|
<!DOCTYPE HTML>
<html lang="en" class="sidebar-visible no-js light">
<head>
<!-- Book generated using mdBook -->
<meta charset="UTF-8">
<title>Notes</title>
<meta name="robots" content="noindex" />
<meta content="text/html; charset=utf-8" http-equiv="Content-Type">
<meta name="description" content="">
<meta name="viewport" content="width=device-width, initial-scale=1">
<meta name="theme-color" content="#ffffff" />
<link rel="shortcut icon" href="favicon.png">
<link rel="stylesheet" href="css/variables.css">
<link rel="stylesheet" href="css/general.css">
<link rel="stylesheet" href="css/chrome.css">
<link rel="stylesheet" href="css/print.css" media="print">
<!-- Fonts -->
<link rel="stylesheet" href="FontAwesome/css/font-awesome.css">
<link href="https://fonts.googleapis.com/css?family=Open+Sans:300italic,400italic,600italic,700italic,800italic,400,300,600,700,800" rel="stylesheet" type="text/css">
<link href="https://fonts.googleapis.com/css?family=Source+Code+Pro:500" rel="stylesheet" type="text/css">
<!-- Highlight.js Stylesheets -->
<link rel="stylesheet" href="highlight.css">
<link rel="stylesheet" href="tomorrow-night.css">
<link rel="stylesheet" href="ayu-highlight.css">
<!-- Custom theme stylesheets -->
</head>
<body>
<!-- Provide site root to javascript -->
<script type="text/javascript">
var path_to_root = "";
var default_theme = window.matchMedia("(prefers-color-scheme: dark)").matches ? "light" : "light";
</script>
<!-- Work around some values being stored in localStorage wrapped in quotes -->
<script type="text/javascript">
try {
var theme = localStorage.getItem('mdbook-theme');
var sidebar = localStorage.getItem('mdbook-sidebar');
if (theme.startsWith('"') && theme.endsWith('"')) {
localStorage.setItem('mdbook-theme', theme.slice(1, theme.length - 1));
}
if (sidebar.startsWith('"') && sidebar.endsWith('"')) {
localStorage.setItem('mdbook-sidebar', sidebar.slice(1, sidebar.length - 1));
}
} catch (e) { }
</script>
<!-- Set the theme before any content is loaded, prevents flash -->
<script type="text/javascript">
var theme;
try { theme = localStorage.getItem('mdbook-theme'); } catch(e) { }
if (theme === null || theme === undefined) { theme = default_theme; }
var html = document.querySelector('html');
html.classList.remove('no-js')
html.classList.remove('light')
html.classList.add(theme);
html.classList.add('js');
</script>
<!-- Hide / unhide sidebar before it is displayed -->
<script type="text/javascript">
var html = document.querySelector('html');
var sidebar = 'hidden';
if (document.body.clientWidth >= 1080) {
try { sidebar = localStorage.getItem('mdbook-sidebar'); } catch(e) { }
sidebar = sidebar || 'visible';
}
html.classList.remove('sidebar-visible');
html.classList.add("sidebar-" + sidebar);
</script>
<nav id="sidebar" class="sidebar" aria-label="Table of contents">
<div id="sidebar-scrollbox" class="sidebar-scrollbox">
<ol class="chapter"><li class="expanded "><a href="tools/index.html"><strong aria-hidden="true">1.</strong> Tools</a></li><li><ol class="section"><li class="expanded "><a href="tools/zsh.html"><strong aria-hidden="true">1.1.</strong> zsh</a></li><li class="expanded "><a href="tools/bash.html"><strong aria-hidden="true">1.2.</strong> bash</a></li><li class="expanded "><a href="tools/fish.html"><strong aria-hidden="true">1.3.</strong> fish</a></li><li class="expanded "><a href="tools/tmux.html"><strong aria-hidden="true">1.4.</strong> tmux</a></li><li class="expanded "><a href="tools/git.html"><strong aria-hidden="true">1.5.</strong> git</a></li><li class="expanded "><a href="tools/awk.html"><strong aria-hidden="true">1.6.</strong> awk</a></li><li class="expanded "><a href="tools/emacs.html"><strong aria-hidden="true">1.7.</strong> emacs</a></li><li class="expanded "><a href="tools/gdb.html"><strong aria-hidden="true">1.8.</strong> gdb</a></li><li class="expanded "><a href="tools/radare2.html"><strong aria-hidden="true">1.9.</strong> radare2</a></li></ol></li><li class="expanded "><a href="monitor/index.html"><strong aria-hidden="true">2.</strong> Resource analysis & monitor</a></li><li><ol class="section"><li class="expanded "><a href="monitor/lsof.html"><strong aria-hidden="true">2.1.</strong> lsof</a></li><li class="expanded "><a href="monitor/pidstat.html"><strong aria-hidden="true">2.2.</strong> pidstat</a></li><li class="expanded "><a href="monitor/pgrep.html"><strong aria-hidden="true">2.3.</strong> pgrep</a></li><li class="expanded "><a href="monitor/pmap.html"><strong aria-hidden="true">2.4.</strong> pmap</a></li><li class="expanded "><a href="monitor/pstack.html"><strong aria-hidden="true">2.5.</strong> pstack</a></li></ol></li><li class="expanded "><a href="trace_profile/index.html"><strong aria-hidden="true">3.</strong> Trace and Profile</a></li><li><ol class="section"><li class="expanded "><a href="trace_profile/strace.html"><strong aria-hidden="true">3.1.</strong> strace</a></li><li class="expanded "><a href="trace_profile/ltrace.html"><strong aria-hidden="true">3.2.</strong> ltrace</a></li><li class="expanded "><a href="trace_profile/perf.html"><strong aria-hidden="true">3.3.</strong> perf</a></li><li class="expanded "><a href="trace_profile/oprofile.html"><strong aria-hidden="true">3.4.</strong> OProfile</a></li><li class="expanded "><a href="trace_profile/time.html"><strong aria-hidden="true">3.5.</strong> time</a></li></ol></li><li class="expanded "><a href="binary/index.html"><strong aria-hidden="true">4.</strong> Binary</a></li><li><ol class="section"><li class="expanded "><a href="binary/od.html"><strong aria-hidden="true">4.1.</strong> od</a></li><li class="expanded "><a href="binary/xxd.html"><strong aria-hidden="true">4.2.</strong> xxd</a></li><li class="expanded "><a href="binary/readelf.html"><strong aria-hidden="true">4.3.</strong> readelf</a></li><li class="expanded "><a href="binary/objdump.html"><strong aria-hidden="true">4.4.</strong> objdump</a></li><li class="expanded "><a href="binary/nm.html"><strong aria-hidden="true">4.5.</strong> nm</a></li></ol></li><li class="expanded "><a href="development/index.html"><strong aria-hidden="true">5.</strong> Development</a></li><li><ol class="section"><li class="expanded "><a href="development/c++filt.html"><strong aria-hidden="true">5.1.</strong> c++filt</a></li><li class="expanded "><a href="development/c++.html"><strong aria-hidden="true">5.2.</strong> c++</a></li><li class="expanded "><a href="development/glibc.html"><strong aria-hidden="true">5.3.</strong> glibc</a></li><li class="expanded "><a href="development/gcc.html"><strong aria-hidden="true">5.4.</strong> gcc</a></li><li class="expanded "><a href="development/ld.so.html"><strong aria-hidden="true">5.5.</strong> ld.so</a></li></ol></li><li class="expanded "><a href="arch/index.html"><strong aria-hidden="true">6.</strong> Arch</a></li><li><ol class="section"><li class="expanded "><a href="arch/x86_64.html"><strong aria-hidden="true">6.1.</strong> x86_64</a></li></ol></li></ol>
</div>
<div id="sidebar-resize-handle" class="sidebar-resize-handle"></div>
</nav>
<div id="page-wrapper" class="page-wrapper">
<div class="page">
<div id="menu-bar" class="menu-bar">
<div id="menu-bar-sticky-container">
<div class="left-buttons">
<button id="sidebar-toggle" class="icon-button" type="button" title="Toggle Table of Contents" aria-label="Toggle Table of Contents" aria-controls="sidebar">
<i class="fa fa-bars"></i>
</button>
<button id="theme-toggle" class="icon-button" type="button" title="Change theme" aria-label="Change theme" aria-haspopup="true" aria-expanded="false" aria-controls="theme-list">
<i class="fa fa-paint-brush"></i>
</button>
<ul id="theme-list" class="theme-popup" aria-label="Themes" role="menu">
<li role="none"><button role="menuitem" class="theme" id="light">Light (default)</button></li>
<li role="none"><button role="menuitem" class="theme" id="rust">Rust</button></li>
<li role="none"><button role="menuitem" class="theme" id="coal">Coal</button></li>
<li role="none"><button role="menuitem" class="theme" id="navy">Navy</button></li>
<li role="none"><button role="menuitem" class="theme" id="ayu">Ayu</button></li>
</ul>
<button id="search-toggle" class="icon-button" type="button" title="Search. (Shortkey: s)" aria-label="Toggle Searchbar" aria-expanded="false" aria-keyshortcuts="S" aria-controls="searchbar">
<i class="fa fa-search"></i>
</button>
</div>
<h1 class="menu-title">Notes</h1>
<div class="right-buttons">
<a href="print.html" title="Print this book" aria-label="Print this book">
<i id="print-button" class="fa fa-print"></i>
</a>
</div>
</div>
</div>
<div id="search-wrapper" class="hidden">
<form id="searchbar-outer" class="searchbar-outer">
<input type="search" name="search" id="searchbar" name="searchbar" placeholder="Search this book ..." aria-controls="searchresults-outer" aria-describedby="searchresults-header">
</form>
<div id="searchresults-outer" class="searchresults-outer hidden">
<div id="searchresults-header" class="searchresults-header"></div>
<ul id="searchresults">
</ul>
</div>
</div>
<!-- Apply ARIA attributes after the sidebar and the sidebar toggle button are added to the DOM -->
<script type="text/javascript">
document.getElementById('sidebar-toggle').setAttribute('aria-expanded', sidebar === 'visible');
document.getElementById('sidebar').setAttribute('aria-hidden', sidebar !== 'visible');
Array.from(document.querySelectorAll('#sidebar a')).forEach(function(link) {
link.setAttribute('tabIndex', sidebar === 'visible' ? 0 : -1);
});
</script>
<div id="content" class="content">
<main>
<h1><a class="header" href="#tools" id="tools">Tools</a></h1>
<ul>
<li><a href="tools/./zsh.html">zsh</a></li>
<li><a href="tools/./bash.html">bash</a></li>
<li><a href="tools/./fish.html">fish</a></li>
<li><a href="tools/./tmux.html">tmux</a></li>
<li><a href="tools/./git.html">git</a></li>
<li><a href="tools/./awk.html">awk</a></li>
<li><a href="tools/./emacs.html">emacs</a></li>
<li><a href="tools/./gdb.html">gdb</a></li>
<li><a href="tools/./radare2.html">radare2</a></li>
</ul>
<h1><a class="header" href="#zsh1" id="zsh1">zsh(1)</a></h1>
<h2><a class="header" href="#keybindings" id="keybindings">Keybindings</a></h2>
<p>Change input mode:</p>
<pre><code class="language-zsh">bindkey -v change to vi keymap
bindkey -e change to emacs keymap
</code></pre>
<p>Define key-mappings:</p>
<pre><code class="language-zsh">bindkey list mappings in current keymap
bindkey in-str cmd create mapping for `in-str` to `cmd`
bindkey -r in-str remove binding for `in-str`
# C-v <key> dump <key> code, which can be used in `in-str`
# zle -l list all functions for keybindings
# man zshzle(1) STANDARD WIDGETS: get description of functions
</code></pre>
<h2><a class="header" href="#completion" id="completion">Completion</a></h2>
<h3><a class="header" href="#installation" id="installation">Installation</a></h3>
<p>Completion functions are provided via files and need to be placed in a location
covered by <code>$fpath</code>. By convention the completion files are names as <code>_<CMD></code>.</p>
<p>A completion skeleton for the command <code>foo</code>, stored in <code>_foo</code></p>
<pre><code class="language-zsh">#compdef _foo foo
function _foo() {
...
}
</code></pre>
<p>Alternatively one can install a completion function explicitly by calling <code>compdef <FUNC> <CMD></code>.</p>
<h3><a class="header" href="#completion-variables" id="completion-variables">Completion Variables</a></h3>
<p>Following variables are available in Completion functions:</p>
<pre><code class="language-zsh">$words # array with command line in words
$#words # number words
$CURRENT # index into $words for cursor position
$words[CURRENT-1] # previous word (relative to cursor position)
</code></pre>
<h3><a class="header" href="#completion-functions" id="completion-functions">Completion Functions</a></h3>
<ul>
<li><code>_describe</code> simple completion, just words + description</li>
<li><code>_arguments</code> sophisticated completion, allow to specify actions</li>
</ul>
<h4><a class="header" href="#completion-with-a-hrefhttpzshsourceforgenetdocreleasecompletion-systemhtmlcompletion-functions_describea" id="completion-with-a-hrefhttpzshsourceforgenetdocreleasecompletion-systemhtmlcompletion-functions_describea">Completion with <a href="http://zsh.sourceforge.net/Doc/Release/Completion-System.html#Completion-Functions"><code>_describe</code></a></a></h4>
<pre><code class="language-zsh">_describe MSG COMP
</code></pre>
<ul>
<li><code>MSG</code> simple string with header message</li>
<li><code>COMP</code> array of completions where each entry is <code>"opt:description"</code></li>
</ul>
<pre><code class="language-zsh">function _foo() {
local -a opts
opts=('bla:desc for bla' 'blu:desc for blu')
_describe 'foo-msg' opts
}
compdef _foo foo
foo <TAB><TAB>
-- foo-msg --
bla -- desc for bla
blu -- desc for blu
</code></pre>
<h4><a class="header" href="#completion-with-a-hrefhttpzshsourceforgenetdocreleasecompletion-systemhtmlcompletion-functions_argumentsa" id="completion-with-a-hrefhttpzshsourceforgenetdocreleasecompletion-systemhtmlcompletion-functions_argumentsa">Completion with <a href="http://zsh.sourceforge.net/Doc/Release/Completion-System.html#Completion-Functions"><code>_arguments</code></a></a></h4>
<pre><code class="language-zsh">_arguments SPEC [SPEC...]
</code></pre>
<p>where <code>SPEC</code> can have one of the following forms:</p>
<ul>
<li><code>OPT[DESC]:MSG:ACTION</code></li>
<li><code>N:MSG:ACTION</code></li>
</ul>
<p>Available actions</p>
<pre><code class="language-zsh">(op1 op2) list possible matches
->VAL set $state=VAL and continue, `$state` can be checked later in switch case
FUNC call func to generate matches
{STR} evaluate `STR` to generate matches
</code></pre>
<h3><a class="header" href="#example" id="example">Example</a></h3>
<p>Skeleton to copy/paste for writing simple completions.</p>
<p>Assume a program <code>foo</code> with the following interface:</p>
<pre><code class="language-zsh">foo -c green|red|blue -s low|high -f <file> -d <dir> -h
</code></pre>
<p>The completion handler could be implemented as follows in a file called <code>_foo</code>:</p>
<pre><code class="language-zsh">#compdef _foo foo
function _foo_color() {
local colors=()
colors+=('green:green color')
colors+=('red:red color')
colors+=('blue:blue color')
_describe "color" colors
}
function _foo() {
_arguments \
"-c[define color]:color:->s_color" \
"-s[select sound]:color:(low high)" \
"-f[select file]:file:_files" \
"-d[select dir]:fir:_files -/" \
"-h[help]"
case $state in
s_color) _foo_color;;
esac
}
</code></pre>
<h1><a class="header" href="#bash1" id="bash1">bash(1)</a></h1>
<h2><a class="header" href="#expansion" id="expansion">Expansion</a></h2>
<h3><a class="header" href="#generator" id="generator">Generator</a></h3>
<pre><code class="language-bash"># generate sequence from n to m
{n..m}
# generate sequence from n to m step by s
{n..m..s}
# expand cartesian product
{a,b}{c,d}
</code></pre>
<h3><a class="header" href="#parameter" id="parameter">Parameter</a></h3>
<pre><code class="language-bash"># default param
bar=${foo:-some_val} # if $foo set, then bar=$foo else bar=some_val
# check param set
bar=${foo:?msg} # if $foo set, then bar=$foo else exit and print msg
# indirect
FOO=foo
BAR=FOO
bar=${!BAR} # deref value of BAR -> bar=$FOO
# prefix
${foo#prefix} # remove prefix when expanding $foo
# suffix
${foo%suffix} # remove suffix when expanding $foo
# substitute
${foo/pattern/string} # replace pattern with string when expanding foo
# pattern starts with
# '/' replace all occurences of pattern
# '#' pattern match at beginning
# '%' pattern match at end
</code></pre>
<blockquote>
<p>Note: <code>prefix</code>/<code>suffix</code>/<code>pattern</code> are expanded as <a href="tools/bash.html#pathname">pathnames</a>.</p>
</blockquote>
<h3><a class="header" href="#pathname" id="pathname">Pathname</a></h3>
<pre><code class="language-bash">* match any string
? match any single char
\\ match backslash
[abc] match any char of 'a' 'b' 'c'
[a-z] match any char between 'a' - 'z'
[^ab] negate, match all not 'a' 'b'
[:class:] match any char in class, available:
alnum,alpha,ascii,blank,cntrl,digit,graph,lower,
print,punct,space,upper,word,xdigit
</code></pre>
<p>Wit <code>extglob</code> shell option enabled it is possible to have more powerful
patterns. In the following <code>pattern-list</code> is one ore more patterns separated
by <code>|</code> char.</p>
<pre><code class="language-bash">?(pattern-list) matches zero or one occurrence of the given patterns
*(pattern-list) matches zero or more occurrences of the given patterns
+(pattern-list) matches one or more occurrences of the given patterns
@(pattern-list) matches one of the given patterns
!(pattern-list) matches anything except one of the given patterns
</code></pre>
<blockquote>
<p>Note: <code>shopt -s extglob</code>/<code>shopt -u extglob</code> to enable/disable <code>extglob</code>
option.</p>
</blockquote>
<h2><a class="header" href="#io-redirection" id="io-redirection">I/O redirection</a></h2>
<blockquote>
<p>Note: The trick with bash I/O redirection is to interpret from left-to-right.</p>
</blockquote>
<pre><code class="language-bash"># stdout & stderr to file
command >file 2>&1
# equivalent
command &>file
# stderr to stdout & stdout to file
command 2>&1 >file
</code></pre>
<h3><a class="header" href="#explanation" id="explanation">Explanation</a></h3>
<pre><code class="language-bash">j>&i
</code></pre>
<p>Duplicate <code>fd i</code> to <code>fd j</code>, making <code>j</code> a copy of <code>i</code>. See <a href="http://man7.org/linux/man-pages/man2/dup.2.html">dup2(2)</a>.</p>
<p>Example:</p>
<pre><code class="language-bash">command 2>&1 >file
</code></pre>
<ol>
<li>duplicate <code>fd 1</code> to <code>fd 2</code>, effectively redirecting <code>stderr</code> to <code>stdout</code></li>
<li>redirect <code>stdout</code> to <code>file</code></li>
</ol>
<h2><a class="header" href="#completion-1" id="completion-1">Completion</a></h2>
<p>The <code>complete</code> builtin is used to interact with the completion system.</p>
<pre><code class="language-bash">complete # print currently installed completion handler
complete -F <func> <cmd> # install <func> as completion handler for <cmd>
complete -r <cmd> # uninstall completion handler for <cmd>
</code></pre>
<p>Variables available in completion functions:</p>
<pre><code class="language-bash"># in
$1 # <cmd>
$2 # current word
$3 # privous word
COMP_WORDS # array with current command line words
COMP_CWORD # index into COMP_WORDS with current cursor position
# out
COMPREPLY # array with possible completions
</code></pre>
<p>The <code>compgen</code> builtin is used to generate possible matches by comparing <code>word</code>
against words generated by <code>option</code>.</p>
<pre><code class="language-bash">compgen [option] [word]
# usefule options:
# -W <list> specify list of possible completions
# -d generate list with dirs
# -f generate list with files
# -u generate list with users
# -e generate list with exported variables
# compare "f" against words "foo" "foobar" "bar" and generate matches
compgen -W "foo foobar bar" "f"
# compare "hom" against file/dir names and generate matches
compgen -d -f "hom"
</code></pre>
<h3><a class="header" href="#example-1" id="example-1">Example</a></h3>
<p>Skeleton to copy/paste for writing simple completions.</p>
<p>Assume a program <code>foo</code> with the following interface:</p>
<pre><code class="language-bash">foo -c green|red|blue -s low|high -f <file> -h
</code></pre>
<p>The completion handler could be implemented as follows:</p>
<pre><code class="language-bash">function _foo() {
local curr=$2
local prev=$3
local opts="-c -s -f -h"
case $prev in
-c) COMPREPLY=( $(compgen -W "green red blue" -- $curr) );;
-s) COMPREPLY=( $(compgen -W "low high" -- $curr) );;
-f) COMPREPLY=( $(compgen -f -- $curr) );;
*) COMPREPLY=( $(compgen -W "$opts" -- $curr) );;
esac
}
complete -F _foo foo
</code></pre>
<h1><a class="header" href="#fish1" id="fish1">fish(1)</a></h1>
<h2><a class="header" href="#quick-info" id="quick-info">Quick Info</a></h2>
<p>Fish initialization file <code>~/.config/fish/config.fish</code></p>
<p>Switch between different key bindings:</p>
<ul>
<li><code>fish_default_key_bindings</code> to use default key bindings</li>
<li><code>fish_vi_key_bindings</code> to use vi key bindings</li>
</ul>
<h2><a class="header" href="#variables" id="variables">Variables</a></h2>
<p>Available scopes</p>
<ul>
<li><code>local</code> variable local to a block</li>
<li><code>global</code> variable global to shell instance</li>
<li><code>universal</code> variable universal to all shell instances + preserved across
shell restart</li>
</ul>
<h3><a class="header" href="#setunset-variables" id="setunset-variables">Set/Unset Variables</a></h3>
<pre><code class="language-text">set <name> [<values>]
-l local scope
-g global scope
-U universal scope
-e erase variable
-S show verbose info
-x export to ENV
-u unexport from ENV
</code></pre>
<h3><a class="header" href="#lists" id="lists">Lists</a></h3>
<p>In <code>fish</code> all variables are lists (start with index <code>1</code>, but lists can't
contain lists.</p>
<pre><code class="language-text">set foo a b c d
echo $foo[1] # a
echo $foo[-1] # d
echo $foo[2..3] # b c
echo $foo[1 3] # a c
</code></pre>
<p><code>$</code> can be seen as dereference operator.</p>
<pre><code class="language-text">set foo a; set a 1337
echo $$foo # outputs 1337
</code></pre>
<p>Cartesian product.</p>
<pre><code class="language-text">echo file.{h,cc}
# file.h file.cc
echo {a,b}{1,2}
# a1 b1 b2
</code></pre>
<h3><a class="header" href="#special-variables-lists" id="special-variables-lists">Special Variables (Lists)</a></h3>
<pre><code class="language-text">$status # exit code of last command
$pipestatus # list of exit codes of pipe chain
$CMD_DURATION # runtime of last command in ms
</code></pre>
<h4><a class="header" href="#path" id="path"><code>*PATH</code></a></h4>
<p>Lists ending with <code>PATH</code> are automatically split at <code>:</code> when used and joined
with <code>:</code> when exported to the environment.</p>
<pre><code class="language-text">set -x BLA_PATH a:b:c:d
echo $BLA_PATH # a b c d
env | grep BLA_PATH # BLA_PATH=a:b:c:d
</code></pre>
<h2><a class="header" href="#command-handling" id="command-handling">Command Handling</a></h2>
<pre><code class="language-text"># sub-commands are not run in quotes
echo "ls output: "(ls)
</code></pre>
<h3><a class="header" href="#io-redirection-1" id="io-redirection-1">I/O redirection</a></h3>
<pre><code class="language-text"># 'noclobber', fail if 'log' already exists
echo foo >? log
</code></pre>
<h2><a class="header" href="#control-flow" id="control-flow">Control Flow</a></h2>
<h3><a class="header" href="#if--else" id="if--else"><code>if</code> / <code>else</code></a></h3>
<pre><code class="language-text">if grep foo bar
# do sth
else if grep foobar bar
# do sth else
else
# do sth else
end
</code></pre>
<h3><a class="header" href="#switch" id="switch"><code>switch</code></a></h3>
<pre><code class="language-text">switch (echo foo)
case 'foo*'
# do start with foo
case bar dudel
# do bar and dudel
case '*'
# do else
end
</code></pre>
<h3><a class="header" href="#while-loop" id="while-loop"><code>while</code> Loop</a></h3>
<pre><code class="language-text">while true
echo foo
end
</code></pre>
<h3><a class="header" href="#for-loop" id="for-loop"><code>for</code> Loop</a></h3>
<pre><code class="language-text">for f in (ls)
echo $f
end
</code></pre>
<h2><a class="header" href="#functions" id="functions">Functions</a></h2>
<p>Function arguments are passed via <code>$argv</code> list.</p>
<pre><code class="language-text">function fn_foo
echo $argv
end
</code></pre>
<h3><a class="header" href="#autoloading" id="autoloading">Autoloading</a></h3>
<p>When running a command fish attempts to autoload a function. The shell looks
for <code><cmd>.fish</code> in the locations defined by <code>$fish_function_path</code> and loads
the function lazily if found.</p>
<p>This is the preferred way over monolithically defining all functions in a
startup script.</p>
<h3><a class="header" href="#helper" id="helper">Helper</a></h3>
<pre><code class="language-text">functions # list al functions
functions foo # describe function 'foo'
functions -e foo # erase function 'foo'
funced foo # edit function 'foo'
# '-e vim' to edit in vim
</code></pre>
<h2><a class="header" href="#prompt" id="prompt">Prompt</a></h2>
<p>The prompt is defined by the output of the <code>fish_prompt</code> function.</p>
<pre><code class="language-text">function fish_prompt
set -l cmd_ret
echo "> "(pwd) $cmd_ret" "
end
</code></pre>
<blockquote>
<p>Use <code>set_color</code> to manipulate terminal colors.</p>
</blockquote>
<h2><a class="header" href="#useful-builtins" id="useful-builtins">Useful Builtins</a></h2>
<pre><code class="language-text"># history
history search <str> # search history for <str>
history merge # merge histories from fish sessions
# list
count $var # count elements in list
# string
string split SEP STRING
</code></pre>
<h2><a class="header" href="#keymaps" id="keymaps">Keymaps</a></h2>
<pre><code class="language-text"> Shift-Tab ........... tab-completion with search
Alt-Up / Alt-Down ... search history with token under the cursor
Alt-l ............... list content of dir under cursor
Alt-p ............... append '2>&1 | less;' to current cmdline
</code></pre>
<h2><a class="header" href="#debug" id="debug">Debug</a></h2>
<pre><code class="language-text"> status print-stack-trace .. prints function stacktrace (can be used in scripts)
breakpoint ................ halt script execution and gives shell (C-d | exit
to continue)
</code></pre>
<h1><a class="header" href="#tmux1" id="tmux1">tmux(1)</a></h1>
<p>Terminology:</p>
<ul>
<li><code>session</code> is a collection of pseudo terminals which can have multiple
<code>windows</code></li>
<li><code>window</code> uses the entire screen and can be split into rectangular <code>panes</code></li>
<li><code>pane</code> is a single pseudo terminal instance</li>
</ul>
<h1><a class="header" href="#tmux-cli" id="tmux-cli">Tmux cli</a></h1>
<pre><code class="language-markdown"># Session
tmux creates new session
tmux ls list running sessions
tmux kill-session -t <s> kill running session <s>
tmux attach -t <s> [-d] attach to session <s>, detach other clients [-d]
tmux detach -s <s> detach all clients from session <s>
# Environment
tmux showenv -g show global tmux environment variables
tmux setenv -g <var> <val> set variable in global tmux env
# Misc
tmux source-file <file> source config <file>
tmux lscm list available tmux commnds
tmux show -g show global tmux options
tmux display <msg> display message in tmux status line
</code></pre>
<h2><a class="header" href="#scripting" id="scripting">Scripting</a></h2>
<pre><code class="language-markdown"># Session
tmux list-sessions -F '#S' list running sessions, only IDs
# Window
tmux list-windows -F '#I' -t <s> list window IDs for session <s>
tmux selectw -t <s>:<w> select window <w> in session <s>
# Pane
tmux list-panes -F '#P' -t <s>:<w> list pane IDs for window <w> in session <s>
tmux selectp -t <s>:<w>.<p> select pane <p> in window <w> in session <s>
# Run commands
tmux send -t <s>:<w>.<p> "ls" C-m send cmds/keys to pane
tmux run -t <p> <sh-cmd> run shell command <sh-cmd> in background and report output on pane -t <p>
</code></pre>
<p>For example cycle through all panes in all windows in all sessions:</p>
<pre><code class="language-bash"># bash
for s in $(tmux list-sessions -F '#S'); do
for w in $(tmux list-windows -F '#I' -t $s); do
for p in $(tmux list-panes -F '#P' -t $s:$w); do
echo $s:$w.$p
done
done
done
</code></pre>
<h1><a class="header" href="#bindings" id="bindings">Bindings</a></h1>
<pre><code class="language-markdown">prefix d detach from current session
prefix c create new window
prefix w open window list
prefix $ rename session
prefix , rename window
prefix . move current window
</code></pre>
<p>Following bindings are specific to my <a href="https://github.com/johannst/dotfiles/blob/master/tmux.conf"><code>tmux.conf</code></a>:</p>
<pre><code class="language-markdown">C-s prefix
# Panes
prefix s horizontal split
prefix v vertical split
prefix f toggle maximize/minimize current pane
# Movement
prefix Tab toggle between window
prefix h move to pane left
prefix j move to pane down
prefix k move to pane up
prefix l move to pane right
# Resize
prefix C-h resize pane left
prefix C-j resize pane down
prefix C-k resize pane up
prefix C-l resize pane right
# Copy/Paste
prefix C-v enter copy mode
prefix C-p paste yanked text
prefix C-b open copy-buffer list
# In Copy Mode
v enable visual mode
y yank selected text
</code></pre>
<h1><a class="header" href="#command-mode" id="command-mode">Command mode</a></h1>
<p>To enter command mode <code>prefix :</code>.</p>
<p>Some useful commands are:</p>
<pre><code class="language-markdown">setw synchronize-panes on/off enables/disables synchronized input to all panes
list-keys -t vi-copy list keymaps for vi-copy mode
</code></pre>
<h1><a class="header" href="#git1" id="git1">git(1)</a></h1>
<h2><a class="header" href="#staging" id="staging">staging</a></h2>
<pre><code class="language-markdown"> git add -p [<file>] ............ partial staging (interactive)
</code></pre>
<h2><a class="header" href="#remote" id="remote">Remote</a></h2>
<pre><code class="language-markdown"> git remote -v .................. list remotes verbose (with URLs)
git remote show [-n] <remote> .. list info for <remote> (like remote HEAD,
remote branches, tracking mapping)
</code></pre>
<h2><a class="header" href="#branching" id="branching">Branching</a></h2>
<pre><code class="language-markdown"> git branch [-a] ................ list available branches; -a to include
remote branches
git branch -vv ................. list branch & annotate with head sha1 &
remote tracking branch
git branch <bname> ............. create branch with name <bname>
git checkout <bname> ........... switch to branch with name <bname>
git checkout --track <branch> .. start to locally track a remote branch
git push -u origin <rbname> .... push branch to origin (or other remote), and
setup <rbname> as tracking branch
</code></pre>
<h2><a class="header" href="#resetting" id="resetting">Resetting</a></h2>
<pre><code class="language-markdown"> git reset [opt] <ref|commit>
opt:
--mixed .................... resets index, but not working tree
--hard ..................... matches the working tree and index to that
of the tree being switched to any changes to
tracked files in the working tree since
<commit> are lost
git reset HEAD <file> .......... remove file from staging
git reset --soft HEAD~1 ........ delete most recent commit but keep work
git reset --hard HEAD~1 ........ delete most recent commit and delete work
</code></pre>
<h2><a class="header" href="#tags" id="tags">Tags</a></h2>
<pre><code class="language-markdown"> git tag -a <tname> -m "descr" ........ creates an annotated tag (full object
containing tagger, date, ...)
git tag -l ........................... list available tags
git checkout tag/<tname> ............. checkout specific tag
git checkout tag/<tname> -b <bname> .. checkout specific tag in a new branch
</code></pre>
<h2><a class="header" href="#diff" id="diff">Diff</a></h2>
<pre><code class="language-markdown"> git diff HEAD:<fname> origin/HEAD:<fname> ... diff files for different refs
git diff -U$(wc -l <fname>) <fname> ......... shows complete file with diffs
instead of usual diff snippets
</code></pre>
<h2><a class="header" href="#log" id="log">Log</a></h2>
<pre><code class="language-markdown"> git log --oneline .... shows log in single line per commit -> alias for
'--pretty=oneline --abbrev-commit'
git log --graph ...... text based graph of commit history
git log --decorate ... decorate log with REFs
</code></pre>
<h2><a class="header" href="#file-history" id="file-history">File history</a></h2>
<pre><code class="language-markdown"> git log -p <file> ......... show commit history + diffs for <file>
git log --oneline <file> .. show commit history for <file> in compact format
</code></pre>
<h2><a class="header" href="#patching" id="patching">Patching</a></h2>
<pre><code class="language-markdown"> git format-patch <opt> <since>/<revision range>
opt:
-N ................... use [PATCH] instead [PATCH n/m] in subject when
generating patch description (for patches spanning
multiple commits)
--start-number <n> ... start output file generation with <n> as start
number instead '1'
since spcifier:
-3 .................. e.g: create a patch from last three commits
<commit hash> ....... create patch with commits starting after <commit hash>
git am <patch> ......... apply patch and create a commit for it
git apply --stat <PATCH> ... see which files the patch would change
git apply --check <PATCH> .. see if the patch can be applied cleanly
git apply <PATCH> .......... apply the patch locally without creating a commit
# eg: generate patches for each commit from initial commit on
git format-patch -N $(git rev-list --max-parents=0 HEAD)
# generate single patch file from a certain commit/ref
git format-patch <COMMIT/REF> --stdout > my-patch.patch
</code></pre>
<h2><a class="header" href="#submodules" id="submodules">Submodules</a></h2>
<pre><code class="language-markdown"> git submodule add <url> [<path>] .......... add new submodule to current project
git clone --recursive <url> ............... clone project and recursively all
submodules (same as using
'git submodule update --init
--recursive' after clone)
git submodule update --init --recursive ... checkout submodules recursively
using the commit listed in the
super-project (in detached HEAD)
git submodule update --remote <submod> .... fetch & merge remote changes for
<submod>, this will pull
origin/HEAD or a branch specified
for the submodule
git diff --submodule ...................... show commits that are part of the
submodule diff
</code></pre>
<h2><a class="header" href="#inspection" id="inspection">Inspection</a></h2>
<pre><code class="language-markdown"> git ls-tree [-r] <ref> .... show git tree for <ref>, -r to recursively ls sub-trees
git show <obj> ............ show <obj>
git cat-file -p <obj> ..... print content of <obj>
</code></pre>
<h2><a class="header" href="#revision-specifier" id="revision-specifier">Revision Specifier</a></h2>
<pre><code class="language-markdown"> HEAD ........ last commit
HEAD~1 ...... last commit-1
HEAD~N ...... last commit-N (linear backwards when in tree structure, check
difference between HEAD^ and HEAD~)
git rev-list --max-parents=0 HEAD ........... first commit
</code></pre>
<h1><a class="header" href="#awk1" id="awk1">awk(1)</a></h1>
<pre><code class="language-markdown">awk [opt] program [input]
-F <sepstr> field separator string (can be regex)
program awk program
input file or stdin if not file given
</code></pre>
<h2><a class="header" href="#input-processing" id="input-processing">Input processing</a></h2>
<p>Input is processed in two stages:</p>
<ol>
<li>Splitting input into a sequence of <code>records</code>.
By default split at <code>newline</code> character, but can be changed via the
builtin <code>RS</code> variable.</li>
<li>Splitting a <code>record</code> into <code>fields</code>. By default strings without <code>whitespace</code>,
but can be changed via the builtin variable <code>FS</code> or command line option
<code>-F</code>.</li>
</ol>
<p>Fields are accessed as follows:</p>
<ul>
<li><code>$0</code> whole <code>record</code></li>
<li><code>$1</code> field one</li>
<li><code>$2</code> field two</li>
<li>...</li>
</ul>
<h2><a class="header" href="#program" id="program">Program</a></h2>
<p>An <code>awk</code> program is composed of pairs of the form:</p>
<pre><code class="language-markdown">pattern { action }
</code></pre>
<p>The program is run against each <code>record</code> in the input stream. If a <code>pattern</code>
matches a <code>record</code> the corresponding <code>action</code> is executed and can access the
<code>fields</code>.</p>
<pre><code class="language-markdown">INPUT
|
v
record ----> ∀ pattern matched
| |
v v
fields ----> run associated action
</code></pre>
<p>Any valid awk <code>expr</code> can be a <code>pattern</code>.</p>
<h3><a class="header" href="#special-pattern" id="special-pattern">Special pattern</a></h3>
<p>awk provides two special patterns, <code>BEGIN</code> and <code>END</code>, which can be used
multiple times. Actions with those patterns are <strong>executed exactly once</strong>.</p>
<ul>
<li><code>BEGIN</code> actions are run before processing the first record</li>
<li><code>END</code> actions are run after processing the last record</li>
</ul>
<h3><a class="header" href="#special-variables" id="special-variables">Special variables</a></h3>
<ul>
<li><code>RS</code> <em>record separator</em>: first char is the record separator, by default
<newline></li>
<li><code>FS</code> <em>field separator</em>: regex to split records into fields, by default
<space></li>
<li><code>NR</code> <em>number record</em>: number of current record</li>
</ul>
<h3><a class="header" href="#special-statements--functions" id="special-statements--functions">Special statements & functions</a></h3>
<ul>
<li>
<p><code>printf "fmt", args...</code></p>
<p>Print format string, args are comma separated.</p>
<ul>
<li><code>%s</code> string</li>
<li><code>%d</code> decimal</li>
<li><code>%x</code> hex</li>
<li><code>%f</code> float</li>
</ul>
<p>Width can be specified as <code>%Ns</code>, this reserves <code>N</code> chars for a string.
For floats one can use <code>%N.Mf</code>, <code>N</code> is the total number including <code>.</code> and
<code>M</code>.</p>
</li>
<li>
<p><code>strftime("fmt")</code></p>
<p>Print time stamp formatted by <code>fmt</code>.</p>
<ul>
<li><code>%Y</code> full year (eg 2020)</li>
<li><code>%m</code> month (01-12)</li>
<li><code>%d</code> day (01-31)</li>
<li><code>%F</code> alias for <code>%Y-%m-%d</code></li>
<li><code>%H</code> hour (00-23)</li>
<li><code>%M</code> minute (00-59)</li>
<li><code>%S</code> second (00-59)</li>
<li><code>%T</code> alias for <code>%H:%M:%S</code></li>
</ul>
</li>
</ul>
<h2><a class="header" href="#examples" id="examples">Examples</a></h2>
<h3><a class="header" href="#filter-records" id="filter-records">Filter records</a></h3>
<pre><code class="language-bash">awk 'NR%2 == 0 { print $0 }' <file>
</code></pre>
<p>The pattern <code>NR%2 == 0</code> matches every second record and the action <code>{ print $0 }</code>
prints the whole record.</p>
<h3><a class="header" href="#capture-in-variables" id="capture-in-variables">Capture in variables</a></h3>
<pre><code class="language-bash"># /proc/<pid>/status
# Name: cat
# ...
# VmRSS: 516 kB
# ...
for f in /proc/*/status; do
cat $f | awk '
/^VmRSS/ { rss = $2/1024 }
/^Name/ { name = $2 }
END { printf "%16s %6d MB\n", name, rss }';
done | sort -k2 -n
</code></pre>
<p>We capture values from <code>VmRSS</code> and <code>Name</code> into variables and print them at the
<code>END</code> once processing all records is done.</p>
<h3><a class="header" href="#run-shell-command-and-capture-output" id="run-shell-command-and-capture-output">Run shell command and capture output</a></h3>
<pre><code class="language-bash">cat /proc/1/status | awk '
/^Pid/ {
"ps --no-header -o user " $2 | getline user;
print user
}'
</code></pre>
<p>We build a <code>ps</code> command line and capture the first line of the processes output
in the <code>user</code> variable and then print it.</p>
<h1><a class="header" href="#emacs1" id="emacs1">emacs(1)</a></h1>
<h2><a class="header" href="#help" id="help">help</a></h2>
<pre><code class="language-markdown"> C-h ? list available help modes
C-h f describe function
C-h v describe variable
C-h c <KEY> print command bound to <KEY>
C-h k <KEY> describe command bound to <KEY>
C-h b list buffer local key-bindings
<kseq> C-h list possible key-bindings with <kseq>
eg C-x C-h -> list key-bindings beginning with C-x
</code></pre>
<h2><a class="header" href="#package-manager" id="package-manager">package manager</a></h2>
<pre><code class="language-markdown"> package-refresh-contents refresh package list
package-list-packages list available/installed packages
</code></pre>
<h2><a class="header" href="#window" id="window">window</a></h2>
<pre><code class="language-markdown"> C-x 0 kill focused window
C-x 1 kill all other windows
C-x 2 split horizontal
C-x 3 split vertical
</code></pre>
<h2><a class="header" href="#yankpaste" id="yankpaste">yank/paste</a></h2>
<pre><code class="language-markdown"> C-<SPACE> set start mark to select text
M-w copy selected text
C-w kill selected text
C-y paste selected text
M-y cycle through kill-ring
</code></pre>
<h2><a class="header" href="#blockrect" id="blockrect">block/rect</a></h2>
<pre><code class="language-markdown"> C-x <SPC> activate rectangle-mark-mode
M-x string-rectangle <RET> insert text in marked rect
</code></pre>
<h2><a class="header" href="#mass-edit" id="mass-edit">mass edit</a></h2>
<pre><code class="language-makrdown"> C-x h mark whole buffer (mark-whole-buffer)
M-x delete-matching-line <RET> delete lines matching regex
M-x % search & replace region (query-replace)
C-M-x % search & replace regex (query-replace-regexp)
</code></pre>
<h2><a class="header" href="#grep" id="grep">grep</a></h2>
<pre><code class="language-markdown"> M-x find-grep <RET> run find-grep result in *grep* buffer
n/p navigate next/previous match in *grep* buffer
</code></pre>
<h2><a class="header" href="#lisp-mode" id="lisp-mode">lisp mode</a></h2>
<pre><code class="language-markdown"> M-x lisp-interaction-mode activate lisp mode
C-M-x evaluate top expr under cursor
C-x C-e eval-last-sexp
C-u C-x C-e eval-last-sexp and prints result in current buffer
</code></pre>
<h2><a class="header" href="#narrow" id="narrow">narrow</a></h2>
<pre><code class="language-markdown"> C-x n n show only focused region (narrow)
C-x n w show whole buffer (wide)
</code></pre>
<h2><a class="header" href="#org" id="org">org</a></h2>
<pre><code class="language-markdown"> M-up/M-down re-arrange items in same hierarchy
M-left/M-right change item hierarchy
C-RET create new item below current
C-S-RET create new TODO item below current
S-left/S-right cycle TODO states
</code></pre>
<h3><a class="header" href="#org-source" id="org-source">org source</a></h3>
<pre><code class="language-markdown"> <s TAB generate a source block
C-c ' edit source block (in lang specific buffer)
C-c C-c eval source block
</code></pre>
<h1><a class="header" href="#gdb1" id="gdb1">gdb(1)</a></h1>
<h1><a class="header" href="#cli" id="cli">CLI</a></h1>
<pre><code class="language-markdown"> gdb [opts] [prg [-c coredump | -p pid]]
gdb [opts] --args prg <prg-args>
opts:
-p <pid> attach to pid
-c <coredump> use <coredump>
-x <file> execute script <file> before prompt
-ex <cmd> execute command <cmd> before prompt
--tty <tty> set I/O tty for debugee
</code></pre>
<h1><a class="header" href="#interactive-usage" id="interactive-usage">Interactive usage</a></h1>
<pre><code class="language-markdown"> tty <tty>
Set <tty> as tty for debugee.
Make sure nobody reads from target tty, easiest is to spawn a shell
and run following in target tty:
> while true; do sleep 1024; done
set follow-fork-mode <child | parent>
Specify which process to follow when debuggee makes a fork(2)
syscall.
sharedlibrary [<regex>]
Load symbols of shared libs loaded by debugee. Optionally use <regex>
to filter libs for symbol loading.
break [-qualified] <sym> thread <tnum>
Set a breakpoint only for a specific thread.
-qualified: Tred <sym> as fully qualified symbol (quiet handy to set
breakpoints on C symbols in C++ contexts)
rbreak <regex>
Set breakpoints matching <regex>, where matching internally is done
on: .*<regex>.*
command [<bp_list>]
Define commands to run after breakpoint hit. If <bp_list> is not
specified attach command to last created breakpoint. Command block
terminated with 'end' token.
<bp_list>: Space separates list, eg 'command 2 5-8' to run command
for breakpoints: 2,5,6,7,8.
info functions [<regex>]
List functions matching <regex>. List all functions if no <regex>
provided.
info variables [<regex>]
List variables matching <regex>. List all variables if no <regex>
provided.
info handle [<signal>]
Print how to handle <signal>. If no <signal> specified print for all
signals.
handle <signal> <action>
Configure how gdb handles <signal> sent to debugee.
<action>:
stop/nostop Catch signal in gdb and break.
print/noprint Print message when gdb catches signal.
pass/nopass Pass signal down to debugee.
catch signal <signal>
Create a catchpoint for <signal>.
</code></pre>
<h1><a class="header" href="#user-commands-macros" id="user-commands-macros">User commands (macros)</a></h1>
<p>Gdb allows to create & document user commands as follows:</p>
<pre><code class="language-markdown"> define <cmd>
# cmds
end
document <cmd>
# docu
end
</code></pre>
<p>To get all user commands or documentations one can use:</p>
<pre><code class="language-markdown"> help user-defined
help <cmd>
</code></pre>
<h1><a class="header" href="#hooks" id="hooks">Hooks</a></h1>
<p>Gdb allows to create two types of command <code>hooks</code></p>
<ul>
<li><code>hook-</code> will be run before <code><cmd></code></li>
<li><code>hookpost-</code> will be run after <code><cmd></code></li>
</ul>
<pre><code class="language-markdown"> define hook-<cmd>
# cmds
end
define hookpost-<cmd>
# cmds
end
</code></pre>
<h1><a class="header" href="#examples-1" id="examples-1">Examples</a></h1>
<h2><a class="header" href="#catch-sigsegv-and-execute-commands" id="catch-sigsegv-and-execute-commands">Catch SIGSEGV and execute commands</a></h2>
<p>This creates a <code>catchpoint</code> for the <code>SIGSEGV</code> signal and attached the <code>command</code>
to it.</p>
<pre><code class="language-markdown"> catch signal SIGSEGV
command
bt
c
end
</code></pre>
<h2><a class="header" href="#run-backtrace-on-thread-1-batch-mode" id="run-backtrace-on-thread-1-batch-mode">Run <code>backtrace</code> on thread 1 (batch mode)</a></h2>
<pre><code class="language-markdown"> gdb --batch -ex 'thread 1' -ex 'bt' -p <pid>
</code></pre>
<h2><a class="header" href="#script-gdb-for-automating-debugging-sessions" id="script-gdb-for-automating-debugging-sessions">Script gdb for automating debugging sessions</a></h2>
<p>To script gdb add commands into a file and pass it to gdb via <code>-x</code>.
For example create <code>run.gdb</code>:</p>
<pre><code class="language-markdown"> set pagination off
break mmap
command
info reg rdi rsi rdx
bt
c
end
#initial drop
c
</code></pre>
<p>This script can be used as:</p>
<pre><code class="language-markdown"> gdb --batch -x ./run.gdb -p <pid>
</code></pre>
<h1><a class="header" href="#know-bugs" id="know-bugs">Know Bugs</a></h1>
<h2><a class="header" href="#workaround-command--finish-bug" id="workaround-command--finish-bug">Workaround <code>command + finish</code> bug</a></h2>
<p>When using <code>finish</code> inside a <code>command</code> block, commands after <code>finish</code> are not
executed. To workaround that bug one can create a wrapper function which calls
<code>finish</code>.</p>
<pre><code class="language-markdown"> define handler
bt
finish
info reg rax
end
command
handler
end
</code></pre>
<h1><a class="header" href="#radare21" id="radare21">radare2(1)</a></h1>
<h2><a class="header" href="#print" id="print">print</a></h2>
<pre><code class="language-markdown">
pd <n> [@ <addr>] # print disassembly for <n> instructions
# with optional temporary seek to <addr>
</code></pre>
<h2><a class="header" href="#flags" id="flags">flags</a></h2>
<pre><code class="language-markdown"> fs # list flag-spaces
fs <fs> # select flag-space <fs>
f # print flags of selected flag-space
</code></pre>
<h2><a class="header" href="#help-1" id="help-1">help</a></h2>
<pre><code class="language-markdown"> ?*~<kw> # '?*' list all commands and '~' grep for <kw>
?*~... # '..' less mode /'...' interactive search
</code></pre>
<h2><a class="header" href="#relocation" id="relocation">relocation</a></h2>
<pre><code class="language-markdown"> > r2 -B <baddr> <exe> # open <exe> mapped to addr <baddr>
oob <addr> # reopen current file at <baddr>
</code></pre>
<h1><a class="header" href="#resource-analysis--monitor" id="resource-analysis--monitor">Resource analysis & monitor</a></h1>
<ul>
<li><a href="monitor/./lsof.html">lsof</a></li>
<li><a href="monitor/./pidstat.html">pidstat</a></li>
<li><a href="monitor/./pgrep.html">pgrep</a></li>
<li><a href="monitor/./pmap.html">pmap</a></li>
<li><a href="monitor/./pstack.html">pstack</a></li>
</ul>
<h1><a class="header" href="#lsof8" id="lsof8">lsof(8)</a></h1>
<pre><code class="language-markdown">lsof
-a ......... AND slection filters instead ORing (OR: default)
-p <pid> ... filter by <pid>
+fg ........ show file flags for file descripros
-n ......... don't convert network addr to hostnames
-P ......... don't convert network port to service names
-i <@h[:p]>. show connections to h (hostname|ip addr) with optional port p
</code></pre>
<pre><code class="language-markdown">file flags:
R/W/RW ..... read/write/read-write
CR ......... create
AP ......... append
TR ......... truncate
</code></pre>
<h1><a class="header" href="#examples-2" id="examples-2">Examples</a></h1>
<h2><a class="header" href="#file-flags" id="file-flags">File flags</a></h2>
<p>Show open files with file flags for process:</p>
<pre><code class="language-markdown">lsof +fg -p <pid>
</code></pre>
<h2><a class="header" href="#open-tcp-connections" id="open-tcp-connections">Open TCP connections</a></h2>
<p>Show open tcp connections for <code>$USER</code>:</p>
<pre><code class="language-markdown">lsof -a -u $USER -i tcp
</code></pre>
<p><strong>Note</strong>: <code>-a</code> <em>ands</em> the results. If <code>-a</code> is not given all open files matching
<code>$USER</code> and all tcp connections are listed (<em>ored</em>).</p>
<h2><a class="header" href="#open-connection-to-specific-host" id="open-connection-to-specific-host">Open connection to specific host</a></h2>
<p>Show open connections to <code>localhost</code> for <code>$USER</code>:</p>
<pre><code class="language-markdown">lsof -a -u $USER -i @localhost
</code></pre>
<h1><a class="header" href="#pidstat1" id="pidstat1">pidstat(1)</a></h1>
<pre><code class="language-markdown">pidstat [opt] [interval] [cont]
-U [user] show username instead UID, optionally only show for user
-r memory statistics
-d I/O statistics
-h single line per process and no lines with average
</code></pre>
<h1><a class="header" href="#page-fault-and-memory-utilization" id="page-fault-and-memory-utilization">Page fault and memory utilization</a></h1>
<pre><code class="language-markdown">pidstat -r -p <pid> [interval] [count]
</code></pre>
<pre><code class="language-markdown">minor_pagefault: Happens when the page needed is already in memory but not
allocated to the faulting process, in that case the kernel
only has to create a new page-table entry pointing to the
shared physical page (not required to load a memory page from
disk).
major_pagefault: Happens when the page needed is NOT in memory, the kernel
has to create a new page-table entry and populate the
physical page (required to load a memory page from disk).
</code></pre>
<h1><a class="header" href="#io-statistics" id="io-statistics">I/O statistics</a></h1>
<pre><code class="language-markdown">pidstat -d -p <pid> [interval] [count]
</code></pre>
<h1><a class="header" href="#pgrep1" id="pgrep1">pgrep(1)</a></h1>
<pre><code class="language-markdown">pgrep [opts] <pattern>
-n only list newest matching process
-u <usr> only show matching for user <usr>
-l additionally list command
-a additionally list command + arguments
</code></pre>
<h2><a class="header" href="#debug-newest-process" id="debug-newest-process">Debug newest process</a></h2>
<p>For example attach gdb to newest zsh process from <code>$USER</code>.</p>
<pre><code class="language-markdown">gdb -p $(pgrep -n -u $USER zsh)
</code></pre>
<h1><a class="header" href="#pmap1" id="pmap1">pmap(1)</a></h1>
<pre><code class="language-markdown">pmap <pid>
Dump virtual memory map of process.
Compared to /proc/<pid>/maps it shows the size of the mappings.
</code></pre>
<h1><a class="header" href="#pstack1" id="pstack1">pstack(1)</a></h1>
<pre><code class="language-markdown">pstack <pid>
Dump stack for all threads of process.
</code></pre>
<h1><a class="header" href="#trace-and-profile" id="trace-and-profile">Trace and Profile</a></h1>
<ul>
<li><a href="trace_profile/./strace.html">strace</a></li>
<li><a href="trace_profile/./ltrace.html">ltrace</a></li>
<li><a href="trace_profile/./perf.html">perf</a></li>
<li><a href="trace_profile/./oprofile.html">OProfile</a></li>
<li><a href="trace_profile/./time.html">time</a></li>
</ul>
<h1><a class="header" href="#strace1" id="strace1">strace(1)</a></h1>
<pre><code class="language-markdown">strace [opts] [prg]
-f .......... follow child processes on fork(2)
-p <pid> .... attach to running process
-s <size> ... max string size, truncate of longer (default: 32)
-e <expr> ... expression for trace filtering
-o <file> ... log output into <file>
-c .......... dump syscall statitics at the end
</code></pre>
<pre><code class="language-markdown"><expr>:
trace=syscall[,syscall] .... trace only syscall listed
trace=file ................. trace all syscall that take a filename as arg
trace=process .............. trace process management related syscalls
trace=signal ............... trace signal related syscalls
signal ..................... trace signals delivered to the process
</code></pre>
<h1><a class="header" href="#examples-3" id="examples-3">Examples</a></h1>
<p>Trace <code>open(2)</code> & <code>socket(2)</code> syscalls for a running process + child processes:</p>
<pre><code class="language-markdown">strace -f -e trace=open,socket -p <pid>
</code></pre>
<p>Trace signals delivered to a running process:</p>
<pre><code class="language-markdown">strace -f -e signal -p <pid>
</code></pre>
<h1><a class="header" href="#ltrace1" id="ltrace1">ltrace(1)</a></h1>
<pre><code class="language-markdown">ltrace [opts] [prg]
-f .......... follow child processes on fork(2)
-p <pid> .... attach to running process
-o <file> ... log output into <file>
-l <filter> . show who calls into lib matched by <filter>
-C .......... demangle
</code></pre>
<h1><a class="header" href="#example-2" id="example-2">Example</a></h1>
<p>List which program/libs call into <code>libstdc++</code>:</p>
<pre><code class="language-bash">ltrace -l '*libstdc++*' -C -o ltrace.log ./main
</code></pre>
<h1><a class="header" href="#perf1" id="perf1">perf(1)</a></h1>
<pre><code class="language-markdown">perf list show supported hw/sw events
perf stat
-p <pid> .. show stats for running process
-I <ms> ... show stats periodically over interval <ms>
-e <ev> ... filter for events
perf top
-p <pid> .. show stats for running process
-F <hz> ... sampling frequency
-K ........ hide kernel threads
perf record
-p <pid> ............... record stats for running process
-F <hz> ................ sampling frequency
--call-graph <method> .. [fp, dwarf, lbr] method how to caputre backtrace
fp : use frame-pointer, need to compile with
-fno-omit-frame-pointer
dwarf: use .cfi debug information
lbr : use hardware last branch record facility
-g ..................... short-hand for --call-graph fp
-e <ev> ................ filter for events
perf report
-n .................... annotate symbols with nr of samples
--stdio ............... report to stdio, if not presen tui mode
-g graph,0.5,caller ... show caller based call chains with value >0.5
</code></pre>
<pre><code class="language-markdown">Useful <ev>:
page-faults
minor-faults
major-faults
cpu-cycles`
task-clock
</code></pre>
<h2><a class="header" href="#a-hrefhttpsgithubcombrendangreggflamegraphflamegrapha" id="a-hrefhttpsgithubcombrendangreggflamegraphflamegrapha"><a href="https://github.com/brendangregg/FlameGraph"><code>Flamegraph</code></a></a></h2>
<h3><a class="header" href="#flamegraph-with-single-event-trace" id="flamegraph-with-single-event-trace">Flamegraph with single event trace</a></h3>
<pre><code class="language-markdown">perf record -g -e cpu-cycles -p <pid>
perf script | FlameGraph/stackcollapse-perf.pl | FlameGraph/flamegraph.pl > cycles-flamegraph.svg
</code></pre>
<h3><a class="header" href="#flamegraph-with-multiple-event-traces" id="flamegraph-with-multiple-event-traces">Flamegraph with multiple event traces</a></h3>
<pre><code class="language-markdown">perf record -g -e cpu-cycles,page-faults -p <pid>
perf script --per-event-dump
# fold & generate as above
</code></pre>
<h1><a class="header" href="#a-hrefhttpsoprofilesourceforgeiooprofilea" id="a-hrefhttpsoprofilesourceforgeiooprofilea"><a href="https://oprofile.sourceforge.io/">OProfile</a></a></h1>
<pre><code class="language-markdown">operf -g -p <pid>
-g ...... caputre call-graph information
opreport [opt] FILE
show time spent per binary image
-l ...... show time spent per symbol
-c ...... show callgraph information (see below)
-a ...... add column with time spent accumulated over child nodes
ophelp show supported hw/sw events
</code></pre>
<h1><a class="header" href="#usrbintime1" id="usrbintime1">/usr/bin/time(1)</a></h1>
<pre><code class="language-markdown"># statistics of process run
/usr/bin/time -v <cmd>
</code></pre>
<h1><a class="header" href="#binary" id="binary">Binary</a></h1>
<ul>
<li><a href="binary/./od.html">od</a></li>
<li><a href="binary/./xxd.html">xxd</a></li>
<li><a href="binary/./readelf.html">readelf</a></li>
<li><a href="binary/./objdump.html">objdump</a></li>
<li><a href="binary/./nm.html">nm</a></li>
</ul>
<h1><a class="header" href="#od1" id="od1">od(1)</a></h1>
<pre><code class="language-markdown"> od [opts] <file>
-An don't print addr info
-tx4 print hex in 4 byte chunks
-ta print as named character
-tc printable chars or backslash escape
-w4 print 4 bytes per line
-j <n> skip <n> bytes from <file> (hex if start with 0x)
-N <n> dump <n> bytes (hex of start with 0x)
</code></pre>
<h2><a class="header" href="#ascii-to-hex-string" id="ascii-to-hex-string">ASCII to hex string</a></h2>
<pre><code class="language-markdown"> echo -n AAAABBBB | od -An -w4 -tx4
>> 41414141
>> 42424242
echo -n '\x7fELF\n' | od -tx1 -ta -tc
>> 0000000 7f 45 4c 46 0a # tx1
>> del E L F nl # ta
>> 177 E L F \n # tc
</code></pre>
<h2><a class="header" href="#extract-parts-of-file" id="extract-parts-of-file">Extract parts of file</a></h2>
<p>For example <code>.rodata</code> section from an elf file. We can use <code>readelf</code> to get the
offset into the file where the <code>.rodata</code> section starts.</p>
<pre><code class="language-markdown"> readelf -W -S foo
>> Section Headers:
>> [Nr] Name Type Address Off Size ES Flg Lk Inf Al
>> ...
>> [15] .rodata PROGBITS 00000000004009c0 0009c0 000030 00 A 0 0 16
</code></pre>
<p>With the offset of <code>-j 0x0009c0</code> we can dump <code>-N 0x30</code> bytes from the beginning of
the <code>.rodata</code> section as follows:</p>
<pre><code class="language-markdown"> od -j 0x0009c0 -N 0x30 -tx4 -w4 foo
>> 0004700 00020001
>> 0004704 00000000
>> *
>> 0004740 00000001
>> 0004744 00000002
>> 0004750 00000003
>> 0004754 00000004
</code></pre>
<p><strong>Note</strong>: Numbers starting with <code>0x</code> will be interpreted as hex by <code>od</code>.</p>
<h1><a class="header" href="#xxd1" id="xxd1">xxd(1)</a></h1>
<pre><code class="language-markdown"> xxd [opts]
-p dump continuous hexdump
-r convert hexdump into binary ('revert')
-e dump as little endian mode
-i output as C array
</code></pre>
<h2><a class="header" href="#ascii-to-hex-stream" id="ascii-to-hex-stream">ASCII to hex stream</a></h2>
<pre><code class="language-markdown"> echo -n 'aabb' | xxd -p
>> 61616262
</code></pre>
<h2><a class="header" href="#hex-to-binary-stream" id="hex-to-binary-stream">Hex to binary stream</a></h2>
<pre><code class="language-markdown"> echo -n '61616262' | xxd -p -r
>> aabb
</code></pre>
<h2><a class="header" href="#ascii-to-binary" id="ascii-to-binary">ASCII to binary</a></h2>
<pre><code class="language-markdown"> echo -n '\x7fELF' | xxd -p | xxd -p -r | file -p -
>> ELF
</code></pre>
<h2><a class="header" href="#ascii-to-c-array-hex-encoded" id="ascii-to-c-array-hex-encoded">ASCII to <code>C</code> array (hex encoded)</a></h2>
<pre><code class="language-markdown"> xxd -i <(echo -n '\x7fELF')
>> unsigned char _proc_self_fd_11[] = {
>> 0x7f, 0x45, 0x4c, 0x46
>> };
>> unsigned int _proc_self_fd_11_len = 4;
</code></pre>
<h1><a class="header" href="#readelf1" id="readelf1">readelf(1)</a></h1>
<pre><code class="language-markdown"> readelf [opts] <elf>
-W|--wide wide output, dont break output at 80 chars
-h print ELF header
-S print section headers
-l print program headers + segment mapping
-d print .dynamic section (dynamic link information)
--syms print symbol tables (.symtab .dynsym)
--dyn-syms print dynamic symbol table (exported symbols for dynamic linker)
-r print relocation sections (.rel.*, .rela.*)
</code></pre>
<h1><a class="header" href="#objdump1" id="objdump1">objdump(1)</a></h1>
<pre><code class="language-markdown"> objdump [opts] <elf>
-M intel use intil syntax
-d disassemble text section
-D disassemble all sections
-S mix disassembly with source code
-C demangle
-j <section> display info for section
--[no-]show-raw-insn [dont] show object code next to disassembly
</code></pre>
<h2><a class="header" href="#disassemble-section" id="disassemble-section">Disassemble section</a></h2>
<p>For example <code>.plt</code> section:</p>
<pre><code class="language-markdown"> objdump -j .plt -d <elf>
</code></pre>
<h1><a class="header" href="#nm1" id="nm1">nm(1)</a></h1>
<pre><code class="language-markdown"> nm [opts] <elf>
-C demangle
-u undefined only
</code></pre>
<h1><a class="header" href="#development" id="development">Development</a></h1>
<ul>
<li><a href="development/./c++filt.html">c++filt</a></li>
<li><a href="development/./c++.html">c++</a></li>
<li><a href="development/./glibc.html">glibc</a></li>
<li><a href="development/./gcc.html">gcc</a></li>
<li><a href="development/./ld.so.html">ld.so</a></li>
</ul>
<h1><a class="header" href="#cfilt1" id="cfilt1">c++filt(1)</a></h1>
<h2><a class="header" href="#demangle-symbol" id="demangle-symbol">Demangle symbol</a></h2>
<pre><code class="language-markdown"> c++-filt <symbol_str>
</code></pre>
<h2><a class="header" href="#demangle-stream" id="demangle-stream">Demangle stream</a></h2>
<p>For example dynamic symbol table:</p>
<pre><code class="language-markdown"> readelf -W --dyn-syms <elf> | c++filt
</code></pre>
<h1><a class="header" href="#c" id="c">c++</a></h1>
<h2><a class="header" href="#type-deduction" id="type-deduction">Type deduction</a></h2>
<p>Force compile error to see what <code>auto</code> is deduced to.</p>
<pre><code class="language-cpp">auto foo = bar();
// force compile error
typename decltype(foo)::_;
</code></pre>
<h1><a class="header" href="#glibc" id="glibc">glibc</a></h1>
<h2><a class="header" href="#malloc-tracer-a-hrefhttpman7orglinuxman-pagesman3mtrace3htmlmtrace3a" id="malloc-tracer-a-hrefhttpman7orglinuxman-pagesman3mtrace3htmlmtrace3a">malloc tracer <a href="http://man7.org/linux/man-pages/man3/mtrace.3.html"><code>mtrace(3)</code></a></a></h2>
<p>Trace memory allocation and de-allocation to detect memory leaks.
Need to call <code>mtrace(3)</code> to install the tracing hooks.</p>
<p>If we can't modify the binary to call <code>mtrace</code> we can create a small shared
library and pre-load it.</p>
<pre><code class="language-c">// libmtrace.c
#include <mcheck.h>
__attribute__((constructor)) static void init_mtrace() { mtrace(); }
</code></pre>
<p>Compile as:</p>
<pre><code class="language-bash">gcc -shared -fPIC -o libmtrace.so libmtrace.c
</code></pre>
<p>To generate the trace file run:</p>
<pre><code class="language-bash">export MALLOC_TRACE=<file>
LD_PRELOAD=./libmtrace.so <binary>
</code></pre>
<p><strong>Note</strong>: If <code>MALLOC_TRACE</code> is not set <code>mtrace</code> won't install tracing hooks.</p>
<p>To get the results of the trace file:</p>
<pre><code class="language-bash">mtrace <binary> $MALLOC_TRACE
</code></pre>
<h2><a class="header" href="#malloc-check-a-hrefhttpman7orglinuxman-pagesman3mallopt3htmlmallopt3a" id="malloc-check-a-hrefhttpman7orglinuxman-pagesman3mallopt3htmlmallopt3a">malloc check <a href="http://man7.org/linux/man-pages/man3/mallopt.3.html"><code>mallopt(3)</code></a></a></h2>
<p>Configure action when glibc detects memory error.</p>
<pre><code class="language-bash">export MALLOC_CHECK_=<N>
</code></pre>
<p>Useful values:</p>
<pre><code class="language-markdown">1 print detailed error & continue
3 print detailed error + stack trace + memory mappings & abort
7 print simple error message + stack trace + memory mappings & abort
</code></pre>
<h1><a class="header" href="#gcc1" id="gcc1">gcc(1)</a></h1>
<h2><a class="header" href="#cli-1" id="cli-1">CLI</a></h2>
<h3><a class="header" href="#preprocessing" id="preprocessing">Preprocessing</a></h3>
<p>While debugging can be helpful to just pre-process files.</p>
<pre><code class="language-bash">gcc -E [-dM] ...
</code></pre>
<ul>
<li><code>-E</code> run only preprocessor</li>
<li><code>-dM</code> list only <code>#define</code> statements</li>
</ul>
<h2><a class="header" href="#a-hrefhttpsgccgnuorgonlinedocsgccother-builtinshtmlbuiltinsa" id="a-hrefhttpsgccgnuorgonlinedocsgccother-builtinshtmlbuiltinsa"><a href="https://gcc.gnu.org/onlinedocs/gcc/Other-Builtins.html">Builtins</a></a></h2>
<h3><a class="header" href="#__builtin_expectexpr-cond" id="__builtin_expectexpr-cond"><code>__builtin_expect(expr, cond)</code></a></h3>
<p>Give the compiler a hint which branch is hot, so it can lay out the code
accordingly to reduce number of jump instructions.
See on <a href="https://godbolt.org/z/MbTHAP">compiler explorer</a>.</p>
<pre><code class="language-bash">echo "
extern void foo();
extern void bar();
void run0(int x) {
if (__builtin_expect(x,0)) { foo(); }
else { bar(); }
}
void run1(int x) {
if (__builtin_expect(x,1)) { foo(); }
else { bar(); }
}
" | gcc -O2 -S -masm=intel -o /dev/stdout -xc -
</code></pre>
<p>Will generate something similar to the following.</p>
<ul>
<li><code>run0</code>: <code>bar</code> is on the path without branch</li>
<li><code>run1</code>: <code>foo</code> is on the path without branch</li>
</ul>
<pre><code class="language-c">run0:
test edi, edi
jne .L4
xor eax, eax
jmp bar
.L4:
xor eax, eax
jmp foo
run1:
test edi, edi
je .L6
xor eax, eax
jmp foo
.L6:
xor eax, eax
jmp bar
</code></pre>
<h1><a class="header" href="#ldso8" id="ldso8">ld.so(8)</a></h1>
<h2><a class="header" href="#environment-variables" id="environment-variables">Environment Variables</a></h2>
<pre><code class="language-console"> LD_PRELOAD=<l_so> colon separated list of libso's to be pre loaded
LD_DEBUG=<opts> comma separated list of debug options
=help list available options
=libs show library search path
=files processing of input files
=symbols show search path for symbol lookup
=bindings show against which definition a symbol is bound
</code></pre>
<h2><a class="header" href="#ld_preload-initialization-order-and-link-map" id="ld_preload-initialization-order-and-link-map">LD_PRELOAD: Initialization Order and Link Map</a></h2>
<p>Libraries specified in <code>LD_PRELOAD</code> are loaded from <code>left-to-right</code> but
initialized from <code>right-to-left</code>.</p>
<pre><code class="language-markdown"> > ldd ./main
>> libc.so.6 => /usr/lib/libc.so.6
> LD_PRELOAD=liba.so:libb.so ./main
-->
preloaded in this order
<--
initialized in this order
</code></pre>
<p>The preload order determines:</p>
<ul>
<li>the order libraries are inserted into the <code>link map</code></li>
<li>the initialization order for libraries</li>
</ul>
<p>For the example listed above the resulting <code>link map</code> will look like the
following:</p>
<pre><code class="language-makrdown"> +------+ +------+ +------+ +------+
| main | -> | liba | -> | libb | -> | libc |
+------+ +------+ +------+ +------+
</code></pre>
<p>This can be seen when running with <code>LD_DEBUG=files</code>:</p>
<pre><code class="language-makrdown"> > LD_DEBUG=files LD_PRELOAD=liba.so:libb.so ./main
# load order (-> determines link map)
>> file=liba.so [0]; generating link map
>> file=libb.so [0]; generating link map
>> file=libc.so.6 [0]; generating link map
# init order
>> calling init: /usr/lib/libc.so.6
>> calling init: <path>/libb.so
>> calling init: <path>/liba.so
>> initialize program: ./main
</code></pre>
<p>To verify the <code>link map</code> order we let <code>ld.so</code> resolve the <code>memcpy(3)</code> libc
symbol (used in <em>main</em>) dynamically, while enabling <code>LD_DEBUG=symbols,bindings</code>
to see the resolving in action.</p>
<pre><code class="language-makrdown"> > LD_DEBUG=symbols,bindings LD_PRELOAD=liba.so:libb.so ./main
>> symbol=memcpy; lookup in file=./main [0]
>> symbol=memcpy; lookup in file=<path>/liba.so [0]
>> symbol=memcpy; lookup in file=<path>/libb.so [0]
>> symbol=memcpy; lookup in file=/usr/lib/libc.so.6 [0]
>> binding file ./main [0] to /usr/lib/libc.so.6 [0]: normal symbol `memcpy' [GLIBC_2.14]
</code></pre>
<h2><a class="header" href="#dynamic-linking-x86_64" id="dynamic-linking-x86_64">Dynamic Linking (x86_64)</a></h2>
<p>Dynamic linking basically works via one indirect jump. It uses a combination of
function trampolines (<code>.plt</code> section) and a function pointer table (<code>.got.plt</code>
section).
On the first call the trampoline sets up some metadata and then jumps to the
<code>ld.so</code> runtime resolve function, which in turn patches the table with the
correct function pointer.</p>
<pre><code class="language-makrdown"> .plt ....... procedure linkage table, contains function trampolines, usually
located in code segment (rx permission)
.got.plt ... global offset table for .plt, holds the function pointer table
</code></pre>
<p>Using <code>radare2</code> we can analyze this in more detail:</p>
<pre><code class="language-makrdown"> [0x00401040]> pd 4 @ section..got.plt
;-- section..got.plt:
;-- .got.plt: ; [22] -rw- section size 32 named .got.plt
;-- _GLOBAL_OFFSET_TABLE_:
[0] 0x00404000 .qword 0x0000000000403e10 ; section..dynamic
[1] 0x00404008 .qword 0x0000000000000000
; CODE XREF from section..plt @ +0x6
[2] 0x00404010 .qword 0x0000000000000000
;-- reloc.puts:
; CODE XREF from sym.imp.puts @ 0x401030
[3] 0x00404018 .qword 0x0000000000401036 ; RELOC 64 puts
[0x00401040]> pd 6 @ section..plt
;-- section..plt:
;-- .plt: ; [12] -r-x section size 32 named .plt
┌─> 0x00401020 ff35e22f0000 push qword [0x00404008]
╎ 0x00401026 ff25e42f0000 jmp qword [0x00404010]
╎ 0x0040102c 0f1f4000 nop dword [rax]
┌ 6: int sym.imp.puts (const char *s);
└ ╎ 0x00401030 ff25e22f0000 jmp qword [reloc.puts]
╎ 0x00401036 6800000000 push 0
└─< 0x0040103b e9e0ffffff jmp sym..plt
</code></pre>
<ul>
<li>At address <code>0x00401030</code> in the <code>.plt</code> section we see the indirect jump for
<code>puts</code> using the function pointer in <code>_GLOBAL_OFFSET_TABLE_[3] (GOT)</code>.</li>
<li><code>GOT[3]</code> initially points to instruction after the <code>puts</code> trampoline
<code>0x00401036</code>.</li>
<li>This pushes the relocation index <code>0</code> and then jumps to the first trampoline
<code>0x00401020</code>.</li>
<li>The first trampoline jumps to <code>GOT[2]</code> which will be filled at program
startup by the <code>ld.so</code> with its resolve function.</li>
<li>The <code>ld.so</code> resolve function fixes the relocation referenced by the
relocation index pushed by the <code>puts</code> trampoline.</li>
<li>The relocation entry at index <code>0</code> tells the resolve function which symbol to
search for and where to put the function pointer:
<pre><code class="language-makrdown"> > readelf -r <main>
>> Relocation section '.rela.plt' at offset 0x4b8 contains 1 entry:
>> Offset Info Type Sym. Value Sym. Name + Addend
>> 000000404018 000200000007 R_X86_64_JUMP_SLO 0000000000000000 puts@GLIBC_2.2.5 + 0
</code></pre>
As we can see the offset from relocation at index <code>0</code> points to <code>GOT[3]</code>.</li>
</ul>
<h1><a class="header" href="#arch" id="arch">Arch</a></h1>
<ul>
<li><a href="arch/./x86_64.html">x86_64</a></li>
</ul>
<h1><a class="header" href="#x86_64" id="x86_64">x86_64</a></h1>
<p>keywords: x86_64, x86, abi</p>
<ul>
<li>64bit synonyms: <code>x86_64</code>, <code>x64</code>, <code>amd64</code>, <code>intel 64</code></li>
<li>32bit synonyms: <code>x86</code>, <code>ia32</code>, <code>i386</code></li>
<li>ISA type: <code>CISC</code></li>
<li>Endianness: <code>little</code></li>
</ul>
<h2><a class="header" href="#registers" id="registers">Registers</a></h2>
<h3><a class="header" href="#general-purpose-register" id="general-purpose-register">General purpose register</a></h3>
<pre><code class="language-markdown">bytes
[7:0] [3:0] [1:0] [1] [0] desc
----------------------------------------------------------
rax eax ax ah al accumulator
rbx ebx bx bh bl base register
rcx ecx cx ch cl counter
rdx edx dx dh dl data register
rsi esi si - sil source index
rdi edi di - dil destination index
rbp ebp bp - bpl base pointer
rsp esp sp - spl stack pointer
r8-15 rNd rNw - rNb
</code></pre>
<h3><a class="header" href="#special-register" id="special-register">Special register</a></h3>
<pre><code class="language-markdown">bytes
[7:0] [3:0] [1:0] desc
---------------------------------------------------
rflags eflags flags flags register
rip eip ip instruction pointer
</code></pre>
<h3><a class="header" href="#flags-register" id="flags-register">FLAGS register</a></h3>
<pre><code class="language-markdown">rflags
bits desc
-----------------------------
[11] OF overflow flag
[10] DF direction flag
[7] SF sign flag
[6] ZF zero flag
[4] AF auxiliary carry flag
[2] PF parity flag
[0] CF carry flag
</code></pre>
<h2><a class="header" href="#addressing" id="addressing">Addressing</a></h2>
<pre><code class="language-asm">movw [rax], rbx // save val in rbx at [rax]
movw [imm], rbx // save val in rbx at [imm]
movw rax, [rbx+4*rcx] // load val at [rbx+4*rcx] into rax
</code></pre>
<p><code>rip</code> relative addressing:</p>
<pre><code class="language-asm">lea rax, [rip+.my_str] // load addr of .my_str into rax
...
.my_str:
.asciz "Foo"
</code></pre>
<h2><a class="header" href="#size-directives" id="size-directives">Size directives</a></h2>
<p>Explicitly specify size of the operation.</p>
<pre><code class="language-nasm">mov byte ptr [rax], 0xff // save 1 byte(s) at [rax]
mov word ptr [rax], 0xff // save 2 byte(s) at [rax]
mov dword ptr [rax], 0xff // save 4 byte(s) at [rax]
mov qword ptr [rax], 0xff // save 8 byte(s) at [rax]
</code></pre>
<h2><a class="header" href="#a-hrefhttpswwwuclibcorgdocspsabi-x86_64pdfsysv-x86_64-abia" id="a-hrefhttpswwwuclibcorgdocspsabi-x86_64pdfsysv-x86_64-abia"><a href="https://www.uclibc.org/docs/psABI-x86_64.pdf">SysV x86_64 ABI</a></a></h2>
<h3><a class="header" href="#passing-arguments-to-functions" id="passing-arguments-to-functions">Passing arguments to functions</a></h3>
<ul>
<li>Integer/Pointer arguments
<pre><code class="language-markdown">reg arg
-----------
rdi 1
rsi 2
rdx 3
rcx 4
r8 5
r9 6
</code></pre>
</li>
<li>Floating point arguments
<pre><code class="language-markdown">reg arg
-----------
xmm0 1
.. ..
xmm7 7
</code></pre>
</li>
<li>Additional arguments are passed on the stack. Arguments are pushed
right-to-left (RTL), meaning next arguments are closer to current <code>rsp</code>.</li>
</ul>
<h3><a class="header" href="#return-values-from-functions" id="return-values-from-functions">Return values from functions</a></h3>
<ul>
<li>Integer/Pointer return values
<pre><code class="language-markdown">reg size
-----------------
rax 64 bit
rax+rdx 128 bit
</code></pre>
</li>
<li>Floating point return values:
<pre><code class="language-markdown">reg size
-------------------
xmm0 64 bit
xmm0+xmm1 128 bit
</code></pre>
</li>
</ul>
<h3><a class="header" href="#caller-saved-registers" id="caller-saved-registers">Caller saved registers</a></h3>
<p>Caller must save these registers if they should be preserved across function
calls.</p>
<ul>
<li><code>rax</code></li>
<li><code>rcx</code></li>
<li><code>rdx</code></li>
<li><code>rsi</code></li>
<li><code>rdi</code></li>
<li><code>rsp</code></li>
<li><code>r8</code> - <code>r11</code></li>
</ul>
<h3><a class="header" href="#callee-saved-registers" id="callee-saved-registers">Callee saved registers</a></h3>
<p>Caller can expect these registers to be preserved across function calls. Callee
must must save these registers in case they are used.</p>
<ul>
<li><code>rbx</code></li>
<li><code>rbp</code></li>
<li><code>r12</code> – <code>r15</code></li>
</ul>
<h3><a class="header" href="#stack" id="stack">Stack</a></h3>
<ul>
<li>grows downwards</li>
<li>frames aligned on 16 byte boundary
<pre><code class="language-text">HI ADDR
| +------------+
| | prev frame |
| +------------+ <--- 16 byte aligned (X & ~0xf)
| [rbp+8] | saved RIP |
| [rbp] | saved RBP |
| [rbp-8] | func stack |
| | ... |
v +------------+
LO ADDR
</code></pre>
</li>
</ul>
<h2><a class="header" href="#references" id="references">References</a></h2>
<ul>
<li><a href="https://www.uclibc.org/docs/psABI-x86_64.pdf">SystemV AMD64 ABI</a></li>
<li><a href="https://www.amd.com/system/files/TechDocs/24592.pdf">AMD64 Vol1: Application Programming</a></li>
<li><a href="https://www.amd.com/system/files/TechDocs/24593.pdf">AMD64 Vol2: System Programming</a></li>
<li><a href="https://www.amd.com/system/files/TechDocs/24594.pdf">AMD64 Vol3: General-Purpose & System Instructions</a></li>
<li><a href="https://cs.brown.edu/courses/cs033/docs/guides/x64_cheatsheet.pdf">X86_64 Cheat-Sheet</a></li>
<li><a href="https://software.intel.com/content/www/us/en/develop/download/intel-64-and-ia-32-architectures-software-developers-manual-volume-1-basic-architecture.html">Intel 64 Vol1: Basic Architecture</a></li>
<li><a href="https://software.intel.com/content/www/us/en/develop/download/intel-64-and-ia-32-architectures-sdm-combined-volumes-2a-2b-2c-and-2d-instruction-set-reference-a-z.html">Intel 64 Vol2: Instruction Set Reference</a></li>
<li><a href="https://software.intel.com/content/www/us/en/develop/download/intel-64-and-ia-32-architectures-sdm-combined-volumes-3a-3b-3c-and-3d-system-programming-guide.html">Intel 64 Vol3: System Programming Guide</a></li>
</ul>
</main>
<nav class="nav-wrapper" aria-label="Page navigation">
<!-- Mobile navigation buttons -->
<div style="clear: both"></div>
</nav>
</div>
</div>
<nav class="nav-wide-wrapper" aria-label="Page navigation">
</nav>
</div>
<script type="text/javascript">
window.playpen_copyable = true;
</script>
<script src="elasticlunr.min.js" type="text/javascript" charset="utf-8"></script>
<script src="mark.min.js" type="text/javascript" charset="utf-8"></script>
<script src="searcher.js" type="text/javascript" charset="utf-8"></script>
<script src="clipboard.min.js" type="text/javascript" charset="utf-8"></script>
<script src="highlight.js" type="text/javascript" charset="utf-8"></script>
<script src="book.js" type="text/javascript" charset="utf-8"></script>
<!-- Custom JS scripts -->
<script type="text/javascript">
window.addEventListener('load', function() {
window.setTimeout(window.print, 100);
});
</script>
</body>
</html>
|
