Wiki: Bash

• Tips for golfing in Bash
• Bash Reference Manual

Basic tips

• Use for …;{ …;} instead of for …;do …;done
• Use eval {0..n} to loop
• Use $[…] instead of $((…)) for arithmetic expansion
• Try to use && or || instead of if
• : is a short command that does nothing
• history -p prints each argument on a new line
• Unset variables evaluate to 0 in arithmetic expressions

Parameter expansion

Parameter expansion is useful to get or replace substrings, get the length of values or change the case of strings.

a="Hello, World!"
echo ${a:0:5}  # Hello
echo ${#a}     # 13
echo ${a//o/O} # HellO, WOrld!
echo ${a@U}    # HELLO, WORLD!
echo ${a@L}    # hello, world!