Echo substrings of a variable

Say you have a variable set in a shell script:

export testPath='/Users/mary/code/thingy.rb'

You can echo that variable as usual:

echo $testPath
# /Users/mary/code/thingy.rb

But you can also get substrings of that variable as you echo it, using substring extraction. The substring extraction syntax is ${variable:offset:length}

echo ${testPath:11}
# /code/thingy.rb

echo ${testPath:12:4}
# code

You can also change the prefix (${variable#prefix}) and suffix (${variable%suffix}):

echo ${testPath#/Users/mary/code/}
# thingy.rb

echo ${testPath%.rb}
# /Users/mary/code/thingy

Tweet