Bash checking if file exists and then check for a substring in the file

Question

I want to check if file exists and then check for a substring in the file

if [ -f /etc/abc.conf ]; then
   if [ grep 'abc.conf' -e 'host.com' ]
    test = 'PASS'
   else 
    test = 'FAIL'
   fi
else
   echo "File doesnot exist"
fi

echo $test

Please let me know if there is a better way to do the same

Are you asking because this snippet doesn't work? Try [shellcheck](https://www.shellcheck.net) to identify the bad and missing syntax. — that other guy, Sep 05 '18 at 18:14
There is a better way, because what you have now is simply broken. — chepner, Sep 05 '18 at 18:50
@BenjaminW. How is that a duplicate? There's not a single word about non-existing files among the answers :-( — steffen, Sep 06 '18 at 08:12

score 2 · Accepted Answer · answered Sep 05 '18 at 18:09

2

Yes, your grep might support the -s argument:

   -s, --no-messages
          Suppress error messages about nonexistent or unreadable files.

So something like this should work:

grep -qs 'abc.conf' '/etc/abc.conf' && test='PASS' || test='FAIL'

answered Sep 05 '18 at 18:09

steffen

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Jack · Answer 2 · 2018-09-05T23:53:56.340

1

Grep returns 2 if file does not exist or is not readable, and 1 if the string is not found.

grep -qs '<string>' file.txt
res=$?
if [ $res -eq 0 ]; then
  test='PASS'
elif [ $res -eq 1 ]; then
  test='FAIL'
elif [ $res -eq 2 ]; then
  echo "Cannot read file"
else
  echo "Unrecognized return code ($res) from grep"
fi

edited Sep 05 '18 at 23:53

answered Sep 05 '18 at 19:46

Jack

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Or `case $? in 0) test='PASS' ;;` etc. (you have extra spaces around `=`, by the way) – Benjamin W. Sep 05 '18 at 20:29
That's what I get for copy-and-paste! :D I'll fix it. Thanks. – Jack Sep 05 '18 at 23:52
`case` is good, but I did not want to add syntax he might not know. – Jack Sep 05 '18 at 23:55

Bash checking if file exists and then check for a substring in the file

2 Answers2