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Linux count string occurrences

How to use grep in Linux to count string occurrences?

grep -oi "error" /home/xlog/xerrorlogs.txt   | wc -l

Sample output:
5 (if there are 5 matches)

Grep will look for the word "error" in xerrorlogs.txt and count its occurrence per line.

Grep will find the string occurrence without case sensitivity.

Grep parameters:
Print only the matched (non-empty) parts of matching lines, with each such part on a separate output line.
Ignore case distinctions, so that characters that differ only in case match each other.
wc - print newline, word, and byte counts for each file
 -l, --lines
              print the newline counts

If "wc -l" is omitted:
grep -oi "error" /home/xlog/xerrorlogs.txt  

Grep will display the match string.

Sample output:

If Grep uses -c parameter:
grep -oic "error" /home/xlog/xerrorlogs.txt 

Sample output:

The output is "4" if there are 5 matches since counting starts at zero, need to pipe to wc -l  to start counting at "1".


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