cut
Extract sections from lines of text
TLDR
Print the fifth character on each line
Print the fifth to tenth character of each line of the specified file
Split each line in a file by a delimiter into fields and print fields two and six (default delimiter is TAB)
Split each line by the specified delimiter and print all from the second field onward
Use space as a delimiter and print only the first 3 fields
Do not print lines that do not contain the delimiter
Print specific fields of lines that use NUL to terminate lines instead of newlines
SYNOPSIS
cut [-b|--bytes=LIST] [-c|--characters=LIST] [-f|--fields=LIST] [-d|--delimiter=DELIM] [-s|--only-delimited] [--output-delimiter=STRING] [--complement] [--help] [--version] [FILE...]
PARAMETERS
-b, --bytes=LIST
select only these bytes
-c, --characters=LIST
select only these characters
-d, --delimiter=DELIM
use DELIM instead of TAB as field delimiter
-f, --fields=LIST
select only these fields (ignore if no DELIM)
--complement
complement the set of selected bytes/characters/fields
--output-delimiter=STRING
use STRING as output delimiter (default: input DELIM)
-s, --only-delimited
do not print lines without DELIM characters
--help
display help and exit
--version
output version information and exit
DESCRIPTION
cut is a standard Unix/Linux utility that removes (or "cuts") specified sections from each line of input files or standard input, outputting the results to standard output. It excels at parsing delimited text files like CSV, TSV, or system logs by selecting bytes (-b), characters (-c), or fields (-f).
Key features include:
- Field selection using a delimiter (default: TAB).
- Support for ranges, lists, or complements in selection lists (e.g., 1-3,5 or 2-).
- Custom output delimiters.
- Option to skip lines without delimiters (-s).
Typical uses: Extract usernames from /etc/passwd with cut -d: -f1 /etc/passwd; grab the first IP octet from logs; or slice fixed-width columns.
It reads from files or stdin, processes line-by-line without regex support, making it faster than awk or sed for simple extractions. However, it assumes uniform line structures and struggles with variable delimiters or quoted fields. For complex parsing, pair with sort or uniq. Always quote lists to avoid shell expansion.
CAVEATS
Byte/character modes (-b/-c) mishandle multi-byte UTF-8; use -f for Unicode. No regex/quoted field support. Fields numbered from 1; empty LIST errors out. Multiple -b/-c/-f combine selections.
LIST SYNTAX
Comma-separated: numbers (1), ranges (1-3, -3, 3-), lists (1,3-5). Repeatable; order preserved.
EXAMPLES
cut -d',' -f2 file.csv (2nd CSV column).
cut -c1-5,10- *.log (chars 1-5+10-).
echo "a:b:c" | cut -d: --fields=1 --complement (b:c)
HISTORY
Introduced in 7th Edition UNIX (1979) by AT&T; POSIX standardized in 1992. Coreutils version maintained by GNU since 1990s, with enhancements like --output-delimiter in GNU extensions.
