CODEWITHSUNDEEP
bashif-statementfind
Village
Village

Reputation: 24423

What is the simplest way to check if a variable matches a line somewhere within a file in BASH?

I need to check if a variable can be found somewhere within a file (matching the exact line from beginning to end), e.g.:

if [ "$find" is in file.txt ]
then
    echo "Found."
else
    echo "Not found."
fi

I have been using grep -c '^$find$' > count.txt, then count="$(cat count.txt)", then checking if $count is greater than "0", but this method seems inefficient.

What is the simplest way to check if a variable is found, in its entirely, as a line somewhere within a file?

Upvotes: 1

Views: 663

Answers (1)

devnull
devnull

Reputation: 123608

Use grep:

grep -q "$find" file.txt && echo "Found." || echo "Not found."

If you want to match the entire line, use the -x option:

grep -xq "$find" file.txt && echo "Found." || echo "Not found."

Quoting man grep:

  -q, --quiet, --silent
          Quiet; do not write anything to standard output.   Exit  immedi-
          ately  with  zero status if any match is found, even if an error
          was detected.  Also see the -s or --no-messages option.

  -x, --line-regexp
          Select only those matches that exactly match the whole line.

The above can also be written as:

if grep -xq "$find" file.txt; then
    echo "Found."
else
    echo "Not found."
fi

Upvotes: 6

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