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Arronical
Asked: 2016-03-04 08:50:02 +0800 CST

How to remove the filename from wc -l output?

  • 772

I want to count the number of lines in a file using wc -l but only output the number, without the following space and filename. Edit from comments: The filename may have numbers in it.

Currently if I do:

wc -l /path/to/file

On a file with 176 lines, the output is:

176 /path/to/file

This is within a bash script, and the resulting number will be assigned as the value of a variable.

bash

3 Answers

  1. Best Answer

    I'd use:

    <file wc -l

    Which contarily to cat file | wc -l doesn't need to fork a shell and to run another process (and runs faster):

    % time </tmp/ramdisk/file wc -l     
8000000
wc -l < /tmp/ramdisk/file  0,07s user 0,06s system 97% cpu 0,132 total
% time cat /tmp/ramdisk/file | wc -l
8000000
cat /tmp/ramdisk/file  0,01s user 0,16s system 80% cpu 0,204 total
wc -l  0,09s user 0,10s system 94% cpu 0,203 total

    (/tmp/ramdisk/file was stored in a ramdisk to take I/O and caching out of the equation.)

    However for small files indeed the difference is neglectable.

    Yet another way would be:

    wc -l file | cut -d ' ' -f 1

    Which in my tests performs approximately the same as <file wc -l.

    • 12

  2. You can do this with a simple one liner using cat. cat deluge1.log | wc -l

    Answer too simple to require a long drawn out answer.

    • 5

  3. another cleaner option wc -l filename | awk '{print $1}

    example list of entries in a file

    bash-4.1$ wc -l ../CBB_Nodes.txt | awk '{print $1}' 
398
bash-4.1$ 
without awk it would have been as usual with the file name. 

bash-4.1$ wc -l ../CBB_Nodes.txt
398 ../CBB_Nodes.txt
bash-4.1$
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