1CUT(1P) POSIX Programmer's Manual CUT(1P)
2
6 This manual page is part of the POSIX Programmer's Manual. The Linux
7 implementation of this interface may differ (consult the corresponding
8 Linux manual page for details of Linux behavior), or the interface may
9 not be implemented on Linux.
10
12 cut — cut out selected fields of each line of a file
13
15 cut -b list [-n] [file...]
16 cut -c list [file...]
18 cut -f list [-d delim] [-s] [file...]
20
22 The cut utility shall cut out bytes (-b option), characters (-c
23 option), or character-delimited fields (-f option) from each line in
24 one or more files, concatenate them, and write them to standard output.
25
27 The cut utility shall conform to the Base Definitions volume of
28 POSIX.1‐2017, Section 12.2, Utility Syntax Guidelines.
29 The application shall ensure that the option-argument list (see options
31 -b, -c, and -f below) is a <comma>-separated list or <blank>-separated
32 list of positive numbers and ranges. Ranges can be in three forms. The
33 first is two positive numbers separated by a <hyphen-minus> (low-high),
34 which represents all fields from the first number to the second number.
35 The second is a positive number preceded by a <hyphen-minus> (-high),
36 which represents all fields from field number 1 to that number. The
37 third is a positive number followed by a <hyphen-minus> (low-), which
38 represents that number to the last field, inclusive. The elements in
39 list can be repeated, can overlap, and can be specified in any order,
40 but the bytes, characters, or fields selected shall be written in the
41 order of the input data. If an element appears in the selection list
42 more than once, it shall be written exactly once.
43 The following options shall be supported:
45 -b list Cut based on a list of bytes. Each selected byte shall be
47 output unless the -n option is also specified. It shall not
48 be an error to select bytes not present in the input line.
49 -c list Cut based on a list of characters. Each selected character
51 shall be output. It shall not be an error to select charac‐
52 ters not present in the input line.
53 -d delim Set the field delimiter to the character delim. The default
55 is the <tab>.
56 -f list Cut based on a list of fields, assumed to be separated in the
58 file by a delimiter character (see -d). Each selected field
59 shall be output. Output fields shall be separated by a single
60 occurrence of the field delimiter character. Lines with no
61 field delimiters shall be passed through intact, unless -s is
62 specified. It shall not be an error to select fields not
63 present in the input line.
64 -n Do not split characters. When specified with the -b option,
66 each element in list of the form low-high (<hyphen-
67 minus>-separated numbers) shall be modified as follows:
68 * If the byte selected by low is not the first byte of a
70 character, low shall be decremented to select the first
71 byte of the character originally selected by low. If the
72 byte selected by high is not the last byte of a charac‐
73 ter, high shall be decremented to select the last byte of
74 the character prior to the character originally selected
75 by high, or zero if there is no prior character. If the
76 resulting range element has high equal to zero or low
77 greater than high, the list element shall be dropped from
78 list for that input line without causing an error.
79 Each element in list of the form low- shall be treated as
81 above with high set to the number of bytes in the current
82 line, not including the terminating <newline>. Each element
83 in list of the form -high shall be treated as above with low
84 set to 1. Each element in list of the form num (a single num‐
85 ber) shall be treated as above with low set to num and high
86 set to num.
87 -s Suppress lines with no delimiter characters, when used with
89 the -f option. Unless specified, lines with no delimiters
90 shall be passed through untouched.
91
93 The following operand shall be supported:
94 file A pathname of an input file. If no file operands are speci‐
96 fied, or if a file operand is '-', the standard input shall
97 be used.
98
100 The standard input shall be used only if no file operands are speci‐
101 fied, or if a file operand is '-'. See the INPUT FILES section.
102
104 The input files shall be text files, except that line lengths shall be
105 unlimited.
106
108 The following environment variables shall affect the execution of cut:
109 LANG Provide a default value for the internationalization vari‐
111 ables that are unset or null. (See the Base Definitions vol‐
112 ume of POSIX.1‐2017, Section 8.2, Internationalization Vari‐
113 ables for the precedence of internationalization variables
114 used to determine the values of locale categories.)
115 LC_ALL If set to a non-empty string value, override the values of
117 all the other internationalization variables.
118 LC_CTYPE Determine the locale for the interpretation of sequences of
120 bytes of text data as characters (for example, single-byte as
121 opposed to multi-byte characters in arguments and input
122 files).
123 LC_MESSAGES
125 Determine the locale that should be used to affect the format
126 and contents of diagnostic messages written to standard
127 error.
128 NLSPATH Determine the location of message catalogs for the processing
130 of LC_MESSAGES.
131
133 Default.
134
136 The cut utility output shall be a concatenation of the selected bytes,
137 characters, or fields (one of the following):
138 "%s\n", <concatenation of bytes>
141 "%s\n", <concatenation of characters>
143 "%s\n", <concatenation of fields and field delimiters>
145
147 The standard error shall be used only for diagnostic messages.
148
150 None.
151
153 None.
154
156 The following exit values shall be returned:
157 0 All input files were output successfully.
159 >0 An error occurred.
161
163 Default.
164 The following sections are informative.
166
168 The cut and fold utilities can be used to create text files out of
169 files with arbitrary line lengths. The cut utility should be used when
170 the number of lines (or records) needs to remain constant. The fold
171 utility should be used when the contents of long lines need to be kept
172 contiguous.
173 Earlier versions of the cut utility worked in an environment where
175 bytes and characters were considered equivalent (modulo <backspace> and
176 <tab> processing in some implementations). In the extended world of
177 multi-byte characters, the new -b option has been added. The -n option
178 (used with -b) allows it to be used to act on bytes rounded to charac‐
179 ter boundaries. The algorithm specified for -n guarantees that:
180 cut -b 1-500 -n file > file1
183 cut -b 501- -n file > file2
184 ends up with all the characters in file appearing exactly once in file1
186 or file2. (There is, however, a <newline> in both file1 and file2 for
187 each <newline> in file.)
188
190 Examples of the option qualifier list:
191 1,4,7 Select the first, fourth, and seventh bytes, characters, or
193 fields and field delimiters.
194 1-3,8 Equivalent to 1,2,3,8.
196 -5,10 Equivalent to 1,2,3,4,5,10.
198 3- Equivalent to third to last, inclusive.
200 The low-high forms are not always equivalent when used with -b and -n
202 and multi-byte characters; see the description of -n.
203 The following command:
205 cut -d : -f 1,6 /etc/passwd
208 reads the System V password file (user database) and produces lines of
210 the form:
211 <user ID>:<home directory>
214 Most utilities in this volume of POSIX.1‐2017 work on text files. The
216 cut utility can be used to turn files with arbitrary line lengths into
217 a set of text files containing the same data. The paste utility can be
218 used to create (or recreate) files with arbitrary line lengths. For
219 example, if file contains long lines:
220 cut -b 1-500 -n file > file1
223 cut -b 501- -n file > file2
224 creates file1 (a text file) with lines no longer than 500 bytes (plus
226 the <newline>) and file2 that contains the remainder of the data from
227 file. (Note that file2 is not a text file if there are lines in file
228 that are longer than 500 + {LINE_MAX} bytes.) The original file can be
229 recreated from file1 and file2 using the command:
230 paste -d "\0" file1 file2 > file
233
235 Some historical implementations do not count <backspace> characters in
236 determining character counts with the -c option. This may be useful for
237 using cut for processing nroff output. It was deliberately decided not
238 to have the -c option treat either <backspace> or <tab> characters in
239 any special fashion. The fold utility does treat these characters spe‐
240 cially.
241 Unlike other utilities, some historical implementations of cut exit
243 after not finding an input file, rather than continuing to process the
244 remaining file operands. This behavior is prohibited by this volume of
245 POSIX.1‐2017, where only the exit status is affected by this problem.
246 The behavior of cut when provided with either mutually-exclusive
248 options or options that do not work logically together has been delib‐
249 erately left unspecified in favor of global wording in Section 1.4,
250 Utility Description Defaults.
251 The OPTIONS section was changed in response to IEEE PASC Interpretation
253 1003.2 #149. The change represents historical practice on all known
254 systems. The original standard was ambiguous on the nature of the out‐
255 put.
256 The list option-arguments are historically used to select the portions
258 of the line to be written, but do not affect the order of the data. For
259 example:
260 echo abcdefghi | cut -c6,2,4-7,1
263 yields "abdefg".
265 A proposal to enhance cut with the following option:
267 -o Preserve the selected field order. When this option is specified,
269 each byte, character, or field (or ranges of such) shall be writ‐
270 ten in the order specified by the list option-argument, even if
271 this requires multiple outputs of the same bytes, characters, or
272 fields.
273 was rejected because this type of enhancement is outside the scope of
275 the IEEE P1003.2b draft standard.
276
278 None.
279
281 Section 2.5, Parameters and Variables, fold, grep, paste
282 The Base Definitions volume of POSIX.1‐2017, Chapter 8, Environment
284 Variables, Section 12.2, Utility Syntax Guidelines
285
287 Portions of this text are reprinted and reproduced in electronic form
288 from IEEE Std 1003.1-2017, Standard for Information Technology -- Por‐
289 table Operating System Interface (POSIX), The Open Group Base Specifi‐
290 cations Issue 7, 2018 Edition, Copyright (C) 2018 by the Institute of
291 Electrical and Electronics Engineers, Inc and The Open Group. In the
292 event of any discrepancy between this version and the original IEEE and
293 The Open Group Standard, the original IEEE and The Open Group Standard
294 is the referee document. The original Standard can be obtained online
295 at http://www.opengroup.org/unix/online.html .
296 Any typographical or formatting errors that appear in this page are
298 most likely to have been introduced during the conversion of the source
299 files to man page format. To report such errors, see https://www.ker‐
300 nel.org/doc/man-pages/reporting_bugs.html .
301IEEE/The Open Group 2017 CUT(1P)