Testing variable for pattern

Question

I need to ensure a variable passed to my shell script matches a certain pattern. var x has to be in the form of AA-X.X.XX (ie AA-1.2.33). If it doesn't match I need to exit.

Any ideas?

score 1 · Answer 1 · answered Jun 06 '13 at 14:21

1

Bash has direct support for regular expressions.

if ! [[ $mystring ~= $pattern ]]; then
    exit
fi

answered Jun 06 '13 at 14:21

kojiro

74,557
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score 0 · Answer 2 · answered Jun 06 '13 at 14:22

0

Use Bash's Double-Bracket Regex Tests

See Conditional Constructs in the GNU Bash Manual for a complete explanation of the =~ binary operator. As an example:

good_string='AA-1.2.33'
bad_string='BB.11.222.333'
regex='^AA-[[:digit:]]\.[[:digit:]]\.[[:digit:]][[:digit:]]$'

[[ "$good_string" =~ $regex ]]
echo $? # 0

[[ "$bad_string" =~ $regex ]]
echo $? # 1

answered Jun 06 '13 at 14:22

Todd A. Jacobs

81,402
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Thank you so much everyone! I think I was being too strict. I ended up using the following as the digit mask can change over time. – MoBarger Jun 06 '13 at 15:03

score 0 · Answer 3 · answered Jun 06 '13 at 14:24

0

Doable directly in bash

var=AA-1.2.33
[[ $var =~ ^AA-.\..\...$ ]]
echo $?
0
var=AA-1.2.3355
[[ $var =~ ^AA-.\..\...$ ]]
echo $?
1

answered Jun 06 '13 at 14:24

iruvar

22,736
7
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`if [[ $myString == AA-* ]] then echo $? # 0 echo "hurray!" else echo $? # 0 echo "nope" fi` – MoBarger Jun 06 '13 at 15:05

Testing variable for pattern

3 Answers3

Use Bash's Double-Bracket Regex Tests