useful bashisms

useful bashisms

#!/bin/bash

# Default variable if not set

[ -z "${var:-}" ] && var="Default..."

echo "$var"

# array declaration

names=(Adam David Johnny Black Abraham)

# array expansion

for item in ${names[@]}; do
    echo "$item"
done

# array count

echo ${#names}

# delete pattern in array
echo ${names[@]##A*} # David Johnny Black

# string operations

str="thisisaverylongstring"

# substrings

echo ${str:4} # isaverylongstring
echo ${str:6:5} # avery

echo ${str%string} # thisisaverylong

# replaces first occurence

echo ${str/i/_i_} # th_i_sisaverylongstring

# replaces every occurence

echo ${str//i/_i_} # th__i__s__i__saverylongstr__i__ng

First one is not Bashism. It is defined by POSIX: http://pubs.opengroup.org/onlinepubs/9699919799//utilities/V3_chap02.html