tr コマンドは便利

最近知った便利なコマンド tr

tr - translate or delete characters

tr str1 str2
str1をstr2に変換する
例)
$ echo "cat" | tr 'c' 'r'
rat

$ echo "Uryyb jbeyq" | tr 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz' 'NOPQRSTUVWXYZABCDEFGHIJKLMnopqrstuvwxyzabcdefghijklm'
Hello world

$ echo "Uryyb jbeyq" | tr 'A-Z' 'N-ZA-M' | tr 'a-z' 'n-za-m'
Hello world

コマンドひとつで換字できるので便利
以上

おまけ


#!/bin/bash

# script to perform ROT13 substitution

raw_table='ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz'
rot_table='NOPQRSTUVWXYZABCDEFGHIJKLMnopqrstuvwxyzabcdefghijklm'

if [ $# -ne 1 ]; then
echo "Usage: $0 [string]"
exit 1
fi

echo $1 | tr "$raw_table" "$rot_table"

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