Consider using `grep -c`SH-2126

Consider using grep -c instead of grep | wc. This is purely a stylistic issue. grep can count lines without piping to wc.

Often this number is only used to see whether there are matches (i.e. == 0). In these cases it's clearer and more efficient to use grep -q and check its exit status:

if grep -q pattern file; then
  echo "The file contains the pattern"
fi

Also note that in foo | grep bar | wc -l, wc will mask the exit code of grep by default and always return success unless a directive like set -o pipefail is present. By instead writing foo | grep -c bar, grep will exit with a non-zero value when there are no matches. This is generally desirable (see below), but may require handling when used with set -e.

Bad Practice

grep foo | wc -l

Recommended:

grep -c foo

For Multiple Files, instead of:

grep foo *.log | wc -l

You can pipe all the file contents into grep (passing the files directly to grep causes -c to print each file's count separately, rather than the total):

cat *.log | grep foo -c

Exceptions

If you find piping to wc is clearer in a given situation it's fine to ignore this issue.