.\" Copyright (c) 2002 Tim J. Robbins.
.\" All rights reserved.
.\"
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.\" modification, are permitted provided that the following conditions
.\" are met:
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.\" $FreeBSD$
.\"
.Dd February 6, 2014
.Dt CSPLIT 1
.Os
.Sh NAME
.Nm csplit
.Nd split files based on context
.Sh SYNOPSIS
.Nm
.Op Fl ks
.Op Fl f Ar prefix
.Op Fl n Ar number
.Ar file args ...
.Sh DESCRIPTION
The
.Nm
utility splits
.Ar file
into pieces using the patterns
.Ar args .
If
.Ar file
is
a dash
.Pq Sq Fl ,
.Nm
reads from standard input.
.Pp
Files are created with a prefix of
.Dq xx
and two decimal digits.
The size of each file is written to standard output
as it is created.
If an error occurs whilst files are being created,
or a
.Dv HUP ,
.Dv INT ,
or
.Dv TERM
signal is received,
all files previously written are removed.
.Pp
The options are as follows:
.Bl -tag -width indent
.It Fl f Ar prefix
Create file names beginning with
.Ar prefix ,
instead of
.Dq Pa xx .
.It Fl k
Do not remove previously created files if an error occurs or a
.Dv HUP ,
.Dv INT ,
or
.Dv TERM
signal is received.
.It Fl n Ar number
Create file names beginning with
.Ar number
of decimal digits after the prefix,
instead of 2.
.It Fl s
Do not write the size of each output file to standard output as it is
created.
.El
.Pp
The
.Ar args
operands may be a combination of the following patterns:
.Bl -tag -width indent
.It Xo
.Sm off
.Cm / Ar regexp Cm / Op Oo Cm + | - Oc Ar offset
.Sm on
.Xc
Create a file containing the input from the current line to (but not including)
the next line matching the given basic regular expression.
An optional
.Ar offset
from the line that matched may be specified.
.It Xo
.Sm off
.Cm % Ar regexp Cm % Op Oo Cm + | - Oc Ar offset
.Sm on
.Xc
Same as above but a file is not created for the output.
.It Ar line_no
Create containing the input from the current line to (but not including)
the specified line number.
.It Cm { Ns Ar num Ns Cm }
Repeat the previous pattern the specified number of times.
If it follows a line number pattern, a new file will be created for each
.Ar line_no
lines,
.Ar num
times.
The first line of the file is line number 1 for historic reasons.
.El
.Pp
After all the patterns have been processed, the remaining input data
(if there is any) will be written to a new file.
.Pp
Requesting to split at a line before the current line number or past the
end of the file will result in an error.
.Sh ENVIRONMENT
The
.Ev LANG , LC_ALL , LC_COLLATE
and
.Ev LC_CTYPE
environment variables affect the execution of
.Nm
as described in
.Xr environ 7 .
.Sh EXIT STATUS
.Ex -std
.Sh EXAMPLES
Split the
.Xr mdoc 7
file
.Pa foo.1
into one file for each section (up to 21 plus one for the rest, if any):
.Pp
.Dl "csplit -k foo.1 '%^\e.Sh%' '/^\e.Sh/' '{20}'"
.Pp
Split standard input after the first 99 lines and every 100 lines thereafter:
.Pp
.Dl "csplit -k - 100 '{19}'"
.Sh SEE ALSO
.Xr sed 1 ,
.Xr split 1 ,
.Xr re_format 7
.Sh STANDARDS
The
.Nm
utility conforms to
.St -p1003.1-2001 .
.Sh HISTORY
A
.Nm
command appeared in PWB UNIX.
.Sh BUGS
Input lines are limited to
.Dv LINE_MAX
(2048) bytes in length.