From 60f9e870747afb67526c226b872694913007b037 Mon Sep 17 00:00:00 2001
From: johannst <johannes.stoelp@gmail.com>
Date: Thu, 10 Sep 2020 23:25:06 +0200
Subject: renamed misc -> tools

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 src/misc/awk.md | 126 --------------------------------------------------------
 1 file changed, 126 deletions(-)
 delete mode 100644 src/misc/awk.md

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diff --git a/src/misc/awk.md b/src/misc/awk.md
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-# awk(1)
-
-```markdown
-awk [opt] program [input]
-    -F <sepstr>        field separator string (can be regex)
-    program            awk program
-    input              file or stdin if not file given
-```
-
-## Input processing
-
-Input is processed in two stages:
-1. Splitting input into a sequence of `records`.
-   By default split at `newline` character, but can be changed via the
-   builtin `RS` variable.
-2. Splitting a `record` into `fields`. By default strings without `whitespace`,
-   but can be changed via the builtin variable `FS` or command line option
-   `-F`.
-
-Fields are accessed as follows:
-- `$0` whole `record`
-- `$1` field one
-- `$2` field two
-- ...
-
-## Program
-
-An `awk` program is composed of pairs of the form:
-```markdown
-pattern { action }
-```
-The program is run against each `record` in the input stream. If a `pattern`
-matches a `record` the corresponding `action` is executed and can access the
-`fields`.
-
-```markdown
-INPUT
-  |
-  v
-record ----> ∀ pattern matched
-  |                   |
-  v                   v
-fields ----> run associated action
-```
-
-Any valid awk `expr` can be a `pattern`.
-
-### Special pattern
-
-awk provides two special patterns, `BEGIN` and `END`, which can be used
-multiple times. Actions with those patterns are **executed exactly once**.
-- `BEGIN` actions are run before processing the first record
-- `END` actions are run after processing the last record
-
-### Special variables
-
-- `RS` _record separator_: first char is the record separator, by default
-  <newline>
-- `FS` _field separator_: regex to split records into fields, by default
-  <space>
-- `NR` _number record_: number of current record
-
-### Special statements & functions
-
-- `printf "fmt", args...`
-
-  Print format string, args are comma separated.
-  - `%s` string
-  - `%d` decimal
-  - `%x` hex
-  - `%f` float
-
-  Width can be specified as `%Ns`, this reserves `N` chars for a string.
-  For floats one can use `%N.Mf`, `N` is the total number including `.` and
-  `M`.
-
-- `strftime("fmt")`
-
-  Print time stamp formatted by `fmt`.
-  - `%Y` full year (eg 2020)
-  - `%m` month (01-12)
-  - `%d` day (01-31)
-  - `%F` alias for `%Y-%m-%d`
-  - `%H` hour (00-23)
-  - `%M` minute (00-59)
-  - `%S` second (00-59)
-  - `%T` alias for `%H:%M:%S`
-
-
-## Examples
-
-### Filter records
-```bash
-awk 'NR%2 == 0 { print $0 }' <file>
-```
-The pattern `NR%2 == 0` matches every second record and the action `{ print $0 }`
-prints the whole record.
-
-### Capture in variables
-```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
-```
-We capture values from `VmRSS` and `Name` into variables and print them at the
-`END` once processing all records is done.
-
-### Run shell command and capture output
-```bash
-cat /proc/1/status | awk '
-                     /^Pid/ {
-                        "ps --no-header -o user " $2 | getline user;
-                         print user
-                     }'
-```
-We build a `ps` command line and capture the first line of the processes output
-in the `user` variable and then print it.
-- 
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