Linux fgrep command

Updated: 06/16/2017 by Computer Hope

About fgrep

fgrep searches for fixed-character strings in a file or files. "Fixed-character" means the string is interpreted literally — metacharacters do not exist, and therefore regular expressions cannot be used.

fgrep is useful when you need to search for strings which contain lots of regular expression metacharacters, such as "$", "^", etc. By specifying that your search string contains fixed characters, you don't need to escape each of them with a backslash.

If your string contains newlines, each line will be considered an individual fixed-character string to be matched in the search.

Running fgrep is the same as running grep with the -F option.

fgrep syntax

fgrep [-b] [-c] [-h] [-i] [-l] [-n] [-s] [-v] [-x] [ -e pattern_list] 
      [-f pattern-file] [pattern] [file]


-b Precede each line by the block number on which it was found. This can be useful in locating block numbers by context (first block is 0).
-c Print only a count of the lines that contain the pattern.
-h Suppress printing of files when searching multiple files.
-i Ignore upper/lower case distinction during comparisons.
-l Print the names of files with matching lines once, separated by new-lines. Does not repeat the names of files when the pattern is found more than once.
-n Precede each line by its line number in the file (first line is 1).
-s Work silently, that is, display nothing except error messages. This is useful for checking the error status.
-v Print all lines except those that contain the pattern.
-x Print only lines matched entirely.
-e pattern_list Search for a string in pattern-list (useful when the string begins with a "-").
-f pattern-file Take the list of patterns from pattern-file.
pattern Specify a pattern to be used during the search for input.
file A path name of a file to be searched for the patterns. If no file operands are specified, the standard input will be used.

fgrep examples

fgrep "support" myfile.txt

Search for "support" in the file myfile.txt.

ed — A simple text editor.
egrep — Filter text which matches an extended regular expression.
grep — Filter text which matches a regular expression.
sed — A utility for filtering and transforming text.
sh — The Bourne shell command interpreter.