bash regex in if statement-CodePudding

I'm trying to add name-checking with regular expression, that passes only characters and digits but no special symbols given from the output. I wrote this code, but it's does not working. It shows "not ok" either when I'm typing only characters with digits or chars special symbols

#!/bin/bash
regex="/^[a-zA-Z0-9_] $/gm"
read -p "Type smth: " text

if [[ $text =~ $regex ]]
then
    echo "ok"
else
    echo "not ok"
fi

Here's the output:

user@localhost:~/Documents/scripts$ ./testregex.sh
Type smth: hello$#!
not ok

user@localhost:~/Documents/scripts$ ./testregex.sh
Type smth: hello
not ok

CodePudding user response：

You can use

if [[ $text =~ ^[[:alnum:]_] $ ]]
then
    echo "ok"
else
    echo "not ok"
fi

Details:

^ - start of string
[[:alnum:]_] - one or more letters, digits or underscores
$ - end of string.

Note the absence of regex delimiter chars.

See the online demo.