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PROLOG | NAME | SYNOPSIS | DESCRIPTION | OPTIONS | OPERANDS | STDIN | INPUT FILES | ENVIRONMENT VARIABLES | ASYNCHRONOUS EVENTS | STDOUT | STDERR | OUTPUT FILES | EXTENDED DESCRIPTION | EXIT STATUS | CONSEQUENCES OF ERRORS | APPLICATION USAGE | EXAMPLES | RATIONALE | FUTURE DIRECTIONS | SEE ALSO | COPYRIGHT |
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CSPLIT(1P) POSIX Programmer's Manual CSPLIT(1P)
This manual page is part of the POSIX Programmer's Manual. The
Linux implementation of this interface may differ (consult the
corresponding Linux manual page for details of Linux behavior), or
the interface may not be implemented on Linux.
csplit — split files based on context
csplit [-ks] [-f prefix] [-n number] file arg...
The csplit utility shall read the file named by the file operand,
write all or part of that file into other files as directed by the
arg operands, and write the sizes of the files.
The csplit utility shall conform to the Base Definitions volume of
POSIX.1‐2017, Section 12.2, Utility Syntax Guidelines.
The following options shall be supported:
-f prefix Name the created files prefix00, prefix01, ..., prefixn.
The default is xx00 ... xxn. If the prefix argument
would create a filename exceeding {NAME_MAX} bytes, an
error shall result, csplit shall exit with a diagnostic
message, and no files shall be created.
-k Leave previously created files intact. By default,
csplit shall remove created files if an error occurs.
-n number Use number decimal digits to form filenames for the file
pieces. The default shall be 2.
-s Suppress the output of file size messages.
The following operands shall be supported:
file The pathname of a text file to be split. If file is '-',
the standard input shall be used.
Each arg operand can be one of the following:
/rexp/[offset]
A file shall be created using the content of the lines
from the current line up to, but not including, the line
that results from the evaluation of the regular
expression with offset, if any, applied. The regular
expression rexp shall follow the rules for basic regular
expressions described in the Base Definitions volume of
POSIX.1‐2017, Section 9.3, Basic Regular Expressions.
The application shall use the sequence "\/" to specify a
<slash> character within the rexp. The optional offset
shall be a positive or negative integer value
representing a number of lines. A positive integer value
can be preceded by '+'. If the selection of lines from
an offset expression of this type would create a file
with zero lines, or one with greater than the number of
lines left in the input file, the results are
unspecified. After the section is created, the current
line shall be set to the line that results from the
evaluation of the regular expression with any offset
applied. If the current line is the first line in the
file and a regular expression operation has not yet been
performed, the pattern match of rexp shall be applied
from the current line to the end of the file.
Otherwise, the pattern match of rexp shall be applied
from the line following the current line to the end of
the file.
%rexp%[offset]
Equivalent to /rexp/[offset], except that no file shall
be created for the selected section of the input file.
The application shall use the sequence "\%" to specify a
<percent-sign> character within the rexp.
line_no Create a file from the current line up to (but not
including) the line number line_no. Lines in the file
shall be numbered starting at one. The current line
becomes line_no.
{num} Repeat operand. This operand can follow any of the
operands described previously. If it follows a rexp type
operand, that operand shall be applied num more times.
If it follows a line_no operand, the file shall be split
every line_no lines, num times, from that point.
An error shall be reported if an operand does not reference a line
between the current position and the end of the file.
See the INPUT FILES section.
The input file shall be a text file.
The following environment variables shall affect the execution of
csplit:
LANG Provide a default value for the internationalization
variables that are unset or null. (See the Base
Definitions volume of POSIX.1‐2017, Section 8.2,
Internationalization Variables for the precedence of
internationalization variables used to determine the
values of locale categories.)
LC_ALL If set to a non-empty string value, override the values
of all the other internationalization variables.
LC_COLLATE
Determine the locale for the behavior of ranges,
equivalence classes, and multi-character collating
elements within regular expressions.
LC_CTYPE Determine the locale for the interpretation of sequences
of bytes of text data as characters (for example,
single-byte as opposed to multi-byte characters in
arguments and input files) and the behavior of character
classes within regular expressions.
LC_MESSAGES
Determine the locale that should be used to affect the
format and contents of diagnostic messages written to
standard error.
NLSPATH Determine the location of message catalogs for the
processing of LC_MESSAGES.
If the -k option is specified, created files shall be retained.
Otherwise, the default action occurs.
Unless the -s option is used, the standard output shall consist of
one line per file created, with a format as follows:
"%d\n", <file size in bytes>
The standard error shall be used only for diagnostic messages.
The output files shall contain portions of the original input
file; otherwise, unchanged.
None.
The following exit values shall be returned:
0 Successful completion.
>0 An error occurred.
By default, created files shall be removed if an error occurs.
When the -k option is specified, created files shall not be
removed if an error occurs.
The following sections are informative.
None.
1. This example creates four files, cobol00 ... cobol03:
csplit -f cobol file '/procedure division/' /par5./ /par16./
After editing the split files, they can be recombined as
follows:
cat cobol0[0-3] > file
Note that this example overwrites the original file.
2. This example would split the file after the first 99 lines,
and every 100 lines thereafter, up to 9999 lines; this is
because lines in the file are numbered from 1 rather than
zero, for historical reasons:
csplit -k file 100 {99}
3. Assuming that prog.c follows the C-language coding convention
of ending routines with a '}' at the beginning of the line,
this example creates a file containing each separate C routine
(up to 21) in prog.c:
csplit -k prog.c '%main(%' '/^}/+1' {20}
The -n option was added to extend the range of filenames that
could be handled.
Consideration was given to adding a -a flag to use the alphabetic
filename generation used by the historical split utility, but the
functionality added by the -n option was deemed to make alphabetic
naming unnecessary.
None.
sed(1p), split(1p)
The Base Definitions volume of POSIX.1‐2017, Chapter 8,
Environment Variables, Section 9.3, Basic Regular Expressions,
Section 12.2, Utility Syntax Guidelines
Portions of this text are reprinted and reproduced in electronic
form from IEEE Std 1003.1-2017, Standard for Information
Technology -- Portable Operating System Interface (POSIX), The
Open Group Base Specifications Issue 7, 2018 Edition, Copyright
(C) 2018 by the Institute of Electrical and Electronics Engineers,
Inc and The Open Group. In the event of any discrepancy between
this version and the original IEEE and The Open Group Standard,
the original IEEE and The Open Group Standard is the referee
document. The original Standard can be obtained online at
http://www.opengroup.org/unix/online.html .
Any typographical or formatting errors that appear in this page
are most likely to have been introduced during the conversion of
the source files to man page format. To report such errors, see
https://www.kernel.org/doc/man-pages/reporting_bugs.html .
IEEE/The Open Group 2017 CSPLIT(1P)
Pages that refer to this page: split(1p)
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HTML rendering created 2025-09-06 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. |
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