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uniq

Reportar u omitir lineas repetidas

Un caso de uso de este comando es cuando queremos obtener las lineas únicas de un fichero o una entrada.

Supongamos que tenemos un fichero de texto ficheroEjemplo.txt y queremos obtener todas las entradas del fichero desechando las duplicadas, el fichero contiene:

item 1
item 1
item 2
item 2
item 3
item 4
item 5
item 6

En este caso el item 1 y 2 se repiten varias veces por lo que si ejecutamos:

cat ficheroEjemplo.txt | uniq

Devolverá

item 1
item 2
item 3
item 4
item 5
item 6

man uniq

NAME

uniq - report or omit repeated lines

SYNOPSIS

uniq [OPTION]... [INPUT [OUTPUT]]

DESCRIPTION

Filter adjacent matching lines from INPUT (or standard input), writing to OUTPUT (or standard output).

With no options, matching lines are merged to the first occurrence.

Mandatory arguments to long options are mandatory for short options too.

  • -c, --count prefix lines by the number of occurrences
  • -d, --repeated only print duplicate lines, one for each group
  • -D print all duplicate lines
  • --all-repeated[=METHOD] like -D, but allow separating groups with an empty line; METHOD={none(default),prepend,separate}
  • -f, --skip-fields=N avoid comparing the first N fields
  • --group[=METHOD] show all items, separating groups with an empty line; METHOD={separate(default),prepend,append,both}
  • -i, --ignore-case ignore differences in case when comparing
  • -s, --skip-chars=N avoid comparing the first N characters
  • -u, --unique only print unique lines
  • -z, --zero-terminated line delimiter is NUL, not newline
  • -w, --check-chars=N compare no more than N characters in lines
  • --help display this help and exit
  • --version output version information and exit

A field is a run of blanks (usually spaces and/or TABs), then non-blank characters. Fields are skipped before chars.

Note: uniq does not detect repeated lines unless they are adjacent. You may want to sort the input first, or use sort -u without uniq. Also, comparisons honor the rules specified by LC_COLLATE.