grep returns nothing

An empty result is usually quoting

grep "it's" file.txt      # single quotes break the shell string
grep 'it'"'"'s' file.txt

grep -c needle file.txt
wc -l file.txt

grep -a needle file.bin

grep -rn --include='*.log' needle .

A bare grep -r on a large tree often reports binary matches as suppressed rather than returning lines.

Scope: failure mode: Why an empty result set is usually a quoting bug.

CliHelper documents failure modes of third-party command line tools. No software is stored or distributed here.