bash - How do I use a regex in a shell script?

Question

I am trying to match a string with a regex in a shell script. This string is a parameter of the script ( $1 ) and it is a date (MM/DD/YYYY) The regex I'm trying to use is :

^d{2}[/-]d{2}[/-]d{4}$

It seems to work, I tried it on several regex tests websites.

My shell code is :

REGEX_DATE="^d{2}[/-]d{2}[/-]d{4}$"
?
echo "$1" | grep -q $REGEX_DATE
echo $?

The "echo $?" returns 1 no matter is the string I'm putting in parameter.

Do you guys have an idea ?

Thanks !

question from:https://stackoverflow.com/questions/35919103/how-do-i-use-a-regex-in-a-shell-script

Answer 1

I think this is what you want:

REGEX_DATE='^d{2}[/-]d{2}[/-]d{4}$'

echo "$1" | grep -P -q $REGEX_DATE
echo $?

I've used the -P switch to get perl regex.