Linux – Grep: count number of matches per line

linuxregex

I'm trying to get the number of matches (in this case occurrences of { or }) in each line of a .tex file.

I know that the -o flag returns only the match, but it returns each match on a new line, even combined with the -n flag. I don't know of anything I could pipe this through to count the repeats. The -c flag only returns the total number of matches in the entire file – maybe I could pipe one line at a time to grep?

Best Answer

grep -o -n '[{}]' <filename> | cut -d : -f 1 | uniq -c

The output will be something like:

3 1
1 2

Meaning 3 occurrences in the first line and 1 in the second.

Taken from https://stackoverflow.com/a/15366097/3378354 .

Related Solutions

Linux – Counting total number of matches with grep instead of just how many lines match

try this:

grep -o -E "your expression" file |wc -l

well, -E is just an example, it could be -P, -F etc. point is -o

test:

kent$  echo "abc xxx yyy"|grep -cP "[a-z]{3}"      
1

kent$  echo "abc xxx yyy"|grep -oP "[a-z]{3}"|wc -l
3

Linux – Matching a number sequence in grep

The {4} is an extended regular expression. grep will not understand it unless you specify the -E option:

-E, --extended-regexp
       Interpret PATTERN as an extended regular expression (ERE, see below).  (-E is specified by POSIX.)

try with

grep -E '[0-9]{4}'

example

$ echo abcd1234abcd | grep -o -E '[0-9]{4}'
1234

you can also use the [:digit:] character class to avoid problems with locales where the order of the symbols could be different:

$ echo abcd1234abcd | grep -o -E '[[:digit]]{4}'
1234

if for any reason you don't want to use extended regular expressions you can use

grep -o '[0-9][0-9][0-9][0-9]'

Best Answer

Related Solutions

Linux – Counting total number of matches with grep instead of just how many lines match

Linux – Matching a number sequence in grep

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