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up vote -4 down vote favorite

file.txt contains:

aa=testing
sss=whoiam
bbb=findme

What command do I use to search for testing and print it?

Expected result:

# you search testing
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1 Answer 1

up vote 4 down vote

You could use grep:

string=testing && grep "$string" file.txt 2>&1 >/dev/null && echo "you search $string"

The string "you search testing" is printed when the string "testing" is found somewhere in the file file.txt.

  • string=testing: set the variable $string
  • grep "$string" file.txt 2>&1 >/dev/null: grep searches for the string in the file. We don't want the output that because both (stdin and stderr) are redirected to /dev/null.
  • echo "you search $string": if everything is succesfull, print the string.

Just change the variable $string for your pattern.

Additional quesitions:

how about if i want to search the value for aa?

With this oneliner the value of aa is search too. The complete content of the file file.txt is gone trough.

i mean my reference is aa not its value(testing)?

Use this:

string=aa && grep "^$string=" file.txt | awk -F= '{printf "you search %s\n", $2}'

This searched for aa as variable name and then prints the value. The output od this would be:

you search testing
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1  
What is the point of using export? –  Bernhard Aug 15 '14 at 7:15
    
@Bernhard true, I see. It's not needed to make it an environment variable. Edited, tanks. –  chaos Aug 15 '14 at 8:21
    
By using grep's -q flag (for 'quiet) mayou can make the oneliner even simpler: string=testing && grep -q "$string" file.txt && echo "you search $string"` –  ph0t0nix Aug 19 '14 at 14:21

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