Search file(s) for lines that match a fixed string
Syntax fgrep <options> ... fgrep is the same as 'grep -F' all other options are the same as grep
It's a popular fallacy that fgrep stands for fast-grep, in fact fgrep means fixed-string grep.
fgrep implements the Aho–Corasick string matching algorithm which is very fast at matching multiple strings in the input stream/file. So if fgrep is used like this:
fgrep -f patternlist.txt largetextfile.txt
it is much faster than
grep -f patternlist.txt largetextfile.txt
Matching a single pattern with fgrep is not significantly faster than grep.
"The knowledge imposes a pattern, and falsifies, For the pattern is new in every moment..." ~ T. S. Eliot
Related linux commands:
egrep - Search file(s) for lines that match an extended expression.
gawk - Find and Replace text within file(s).
grep - Search file(s) for lines that match a given pattern.
Equivalent Windows command: FINDSTR - Search for strings in files.