grep question

sudz28 · 01-20-2009, 10:54 AM

Linux/Unix newbie here with a quick and hopefully easy grep question. I have a log file I wish to go through and give me a count of the number of times a particular string is encountered; but, I want to be able to print back to the screen what it is I'm giving a number for, since I'm searching for several things. I have a few lines in my script file that say:
tail -100000 nameof.log | fgrep word | wc -l
If I run this it gives me a correct count, but just the number. How do I get it to let me print the word I'm searching for ahead of the count?
Thanks!

Hobbletoe · 01-20-2009, 12:12 PM

Well, you could shove that number into a variable

Code:

word_count=$(tail -100000 nameof.log) | fgrep word | wc -l)
echo word ${word_count}

or, you could do it all in the echo

Code:

echo word $(tail -100000 nameof.log) | fgrep word | wc -l)

The $( ) construct in bash allows you to run a command within a command. Very handy. Have a look at the Bash Guide for Beginners or the Advanced Bash Scripting Guide depending on how comfortable you are with Bash.

PTrenholme · 01-20-2009, 01:58 PM

You could use the tee function, like this for example:

$ tail -100000 nameof.log | grep word | tee /dev/stderr | wc -l

That puts the matched line on stderr followed by the line count. If, instead, you want the information in a file, say "word.matched", something like this should work:

$ word="regexp";tail -100000 nameof.log | grep "$(word)" | tee "$(word)".matched | wc -l >> "$(word)".matched

colucix · 01-20-2009, 02:23 PM

Or use awk:

Code:

$ cat testfile
hello pluto
hello mickey
ciao pippo
hello donald
$ word=hello
$ awk -v pattern=$word '$0 ~ pattern{count++}END{print pattern,"matches",count,"times"}' testfile
hello matches 3 times
$

PTrenholme · 01-21-2009, 07:13 PM

Quote:

Originally Posted by colucix

Or use awk:

Code:

$ cat testfile
hello pluto
hello mickey
ciao pippo
hello donald
$ word=hello
$ awk -v pattern=$word '$0 ~ pattern{count++}END{print pattern,"matches",count,"times"}' testfile
hello matches 3 times
$

Well, sure, although the OP did specify grep.

A slight change to the above program will also print each line containing a match:

awk -v pattern="${word}" '$0 ~ pattern{count++;print;}END{print pattern,"matches",count,"times"}'