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I want to test if an augment (e.g. -h) was passed into my bash script or not.
In a Ruby script that would be:
#!/usr/bin/env ruby
puts "Has -h" if ARGV.include? "-h"
How to best do that in Bash?
387
You can use either "=" or "==" operators for string comparison in bash. The important factor is the spacing within the brackets.
To find out if a bash variable is empty: Return true if a bash variable is unset or set to the empty string: if [ -z "$var" ]; Another option: [ -z "$var" ] && echo "Empty" Determine if a bash variable is empty: [[ ! -z "$var" ]] && echo "Not empty" || echo "Empty"
The if [ $# -eq 0 ] part you can add to the script, and change the 0 to some other numbers to see what happens. Also, an internet search for "bash if" will reveal the meaning of the -eq part, and show that you could also use -lt or -gt , for instance, testing whether a number is less than or greater than another.
The simplest solution would be:
if [[ " $@ " =~ " -h " ]]; then
echo "Has -h"
fi
#!/bin/bash
while getopts h x; do
echo "has -h";
done; OPTIND=0
As Jonathan Leffler pointed out OPTIND=0 will reset the getopts list. That's in case the test needs to be done more than once.
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