CODEWITHSUNDEEP
regexbashshellgrep
tubs
tubs

Reputation: 151

grep variable rather than file

I want to be able to check if a variable containing a string matches a regular expression pattern. I know how to do this with a file using grep but I want to be able to do it using just a string.

For example to find if a variable contains a file name for a .gif I want to be able to do something along the lines of this.

$ STRING=image.gif
$ grep "\.gif$" $STRING

When I run this I get this error.

grep: image.gif: No such file or directory

Is there a way I can get grep treat "image.gif" as the string I want to search rather than the name of a file?

Upvotes: 0

Views: 928

Answers (2)

ray
ray

Reputation: 4267

You can use a bash "here string" to grep from a variable:

grep '\.gif$' <<< "$STRING"

Upvotes: 4

Chris Hayes
Chris Hayes

Reputation: 12050

The easiest way:

echo "$STRING" | grep "\.gif$"

Since grep is capable of reading from stdin you can adapt this to any number of situations (including file IO with cat, though that's generally a bad idea because streaming is more efficient).

Upvotes: 2

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