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takeshin
Asked: 2010-06-21 12:12:51 +0800 CST

echo based on grep result

  • 772

I need a one liner which displays 'yes' or 'no' whether grep finds any results.

I have played with grep -c, but without success.

scripting bash grep

3 Answers

  1. Best Answer

    How about:

    uptime | grep user && echo 'yes' || echo 'no'
uptime | grep foo && echo 'yes' || echo 'no'

    Then you can have it quiet:

    uptime | grep --quiet user && echo 'yes' || echo 'no'
uptime | grep --quiet foo && echo 'yes' || echo 'no'

    From the grep manual page:

    EXIT STATUS

    Normally, the exit status is 0 if selected lines are found and 1 otherwise. But the exit status is 2 if an error occurred, unless the -q or --quiet or --silent option is used and a selected line is found.

    • 11

  2. Not sure what you mean by "one liner", for me this is a "one liner"

    Just add ; if [ $? -eq 0 ]; then echo "Yes"; else echo "No"; fi after you grep command

    bash$ grep ABCDEF /etc/resolv.conf; if [ $? -eq 0 ]; then echo "Yes"; else echo "No"; fi
No
bash$ grep nameserver /etc/resolv.conf; if [ $? -eq 0 ]; then echo "Yes"; else echo "No"; fi
nameserver 212.27.54.252
Yes

    Add -q flag to grep if you want to supress grep result

    bash$ grep -q nameserver /etc/resolv.conf; if [ $? -eq 0 ]; then echo "Yes"; else echo "No"; fi
Yes
    • 2

  3. This version is intermediate between Weboide's version and radius's version:

    if grep --quiet foo bar; then echo "yes"; else echo "no"; fi

    It's more readable than the former and it doesn't unnecessarily use $? like the latter.

    • 2