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+# tr(1)
+
+```
+tr [opt] str1 [str2]
+    -d      delete characters in str1
+    -s      squeeze repeating sequence of characters in str1
+```
+
+## Examples
+
+### To lower
+```sh
+echo MoOsE | tr '[:upper:]' '[:lower:]'
+# output: moose
+```
+
+### Replace characters
+```sh
+echo moose | tr 'o' '-'
+# output: m--se
+
+echo moose | tr 'os' '-'
+# output: m---e
+```
+
+### Remove specific characters
+```sh
+echo moose | tr -d 'o'
+# output: mse
+
+echo moose | tr -d 'os'
+# output: me
+```
+
+### Squeeze character sequences
+```sh
+echo moooooossse | tr -s 'os'
+# output: mose
+```