NAME
uniq —
report or filter out repeated
lines in a file
SYNOPSIS
uniq |
[-cdu]
[-f
fields]
[-s chars]
[input_file
[output_file]] |
DESCRIPTION
The
uniq utility reads the standard input comparing adjacent
lines, and writes a copy of each unique input line to the standard output. The
second and succeeding copies of identical adjacent input lines are not
written. Repeated lines in the input will not be detected if they are not
adjacent, so it may be necessary to sort the files first.
The following options are available:
-
-
- -c
- Precede each output line with the count of the number of
times the line occurred in the input, followed by a single space.
-
-
- -d
- Don't output lines that are not repeated in the input.
-
-
- -f
fields
- Ignore the first fields in each input
line when doing comparisons. A field is a string of non-blank characters
separated from adjacent fields by blanks. Field numbers are one based,
i.e., the first field is field one.
-
-
- -s
chars
- Ignore the first chars characters in
each input line when doing comparisons. If specified in conjunction with
the -f option, the first chars
characters after the first fields fields will be
ignored. Character numbers are one based, i.e., the first character is
character one.
-
-
- -u
- Don't output lines that are repeated in the input.
Additional arguments
input_file and
output_file may be specified on the command line, where
the former is then used as the name of an input file, and the latter as the
name of an output file.
EXIT STATUS
The
uniq utility exits 0 on success, and >0 if an
error occurs.
COMPATIBILITY
The historic
+number and
-number options have been deprecated
but are still supported in this implementation.
SEE ALSO
sort(1)
STANDARDS
The
uniq utility is expected to be
IEEE Std
1003.2 (“POSIX.2”) compatible.