grep - search for pattern in file or folders

Example

grep [OPTIONS] 'PATTERN' FILE

Search pattern ignoring case

grep -i PATTERN FILE

Search pattern and get NEXT NUMBER of lines

grep -A NUMBER PATTERN FILE

Search pattern and get previous NUMBER of lines

grep -B NUMBER PATTERN FILE

Print to stdout all lines of file.txt which match some regex. The example prints lines which begin with “foo” and end in “bar”

grep "^foo.*bar$" file.txt

Pass the option “-c” to instead print the number of lines matching the regex

grep -c "^foo.*bar$" file.txt

Other useful options are:

grep -r "^foo.*bar$" someDir/ # recursively `grep`
grep -n "^foo.*bar$" file.txt # give line numbers
grep -rI "^foo.*bar$" someDir/ # recursively `grep`, but ignore binary files

Perform the same initial search, but filter out the lines containing “baz”

grep "^foo.*bar$" file.txt | grep -v "baz"

If you literally want to search for the string, and not the regex, use fgrep (or grep -F)

fgrep "foobar" file.txt