04 Jan 2012 @ 8:00 PM 

Hello, and thank you for coming again !

I have noticed that some of you are coming via the RSS feed, and it is nice to see you are following this blog thoroughly !

Today, the topic is ” Equal Tilde operator”

The situation

You have a variable, and you need to check if the content is a single digit, or the letter “a” or the letter “A” or the letter “b” or the letter “B”

The solution

You do not use the equal tilde and you die of boredom :

if [[ ${var} = [0-9] ]] || [ “$var” = “a” ] || [ “$var” = “A” ] || [ “$var” = “b” ] || [ “$var” = “B” ] ; then

or you use the equal tile operator :

if [[ “${var}” =~ \^\[0-9]\|a\|b\|A\|B\$ ]] ; then

and you can live another day.

The equal tilde operator allows you to use regex (the same ones you used for see, remember ?) in an if command.

Note the two square brackets.

Thank you for reading, and see you tomorrow !


Nota bene :

You should not put the right side of the =~ operator in quotes, as this will mean a string, and not a regex.

If you do not want escaping everything that might need to be escaping, just put your complicated regex in a variable :

RegEx=”My Complicated Regex”

if [[ “${var}” =~ ${RegEx} ]]; then


Posted By: Dimi
Last Edit: 05 Jan 2012 @ 07:54 PM



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