How can I count the number of lines matching a pattern returned from a linux command

Question

I want the number of lines returned beginning with 'foo' , so if I pipe the output to grep will this work?

cat | grep -c ^foo

Why do you even ask, if you answered the question by yourself. Or simply check with your next nearest shell. — Roman, Feb 19 '13 at 12:36
Useless use of cat. `grep -c pattern file`. Yes it's not that much but as soon as you run that thru a loop that runs a couple of thousand times you'll want to save on forks — serverhorror, Feb 19 '13 at 13:17
Then you could instead ask for alternate ways. Also Server Horror's comment should be an answer. — Alex Hall, Dec 14 '17 at 00:05

score 6 · Answer 1 · edited Feb 19 '13 at 13:16

6

cat | grep ^foo | wc -l

TO show how many lines containing foo are there.

edited Feb 19 '13 at 13:16

MadHatter

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answered Feb 19 '13 at 12:32

Soham Chakraborty

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score 3 · Answer 2 · answered Feb 19 '13 at 12:47

From grep man page:

****General Output Control****
    -c, --count      Suppress normal output;
instead print a count of matching lines for each input file. With the -v, --invert-match option (see below), count non-matching lines. (-c is specified by POSIX.)

score 3 · Answer 3 · answered Dec 14 '17 at 00:06

3

Per Server Horror's comment:

grep -c pattern file

answered Dec 14 '17 at 00:06

Alex Hall

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How can I count the number of lines matching a pattern returned from a linux command

3 Answers3