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.TH MERGE 1 \*(Dt GNU
.SH NAME
merge \- three-way file merge
.SH SYNOPSIS
.B merge
[
.I "options"
]
.I "file1 file2 file3"
.SH DESCRIPTION
.B merge
incorporates all changes that lead from
.I file2
to
.I file3
into
.IR file1 .
The result ordinarily goes into
.IR file1 .
.B merge
is useful for combining separate changes to an original.  Suppose
.I file2
is the original, and both
.I file1
and
.I file3
are modifications of
.IR file2 .
Then
.B merge
combines both changes.
.PP
A conflict occurs if both
.I file1
and
.I file3
have changes in a common segment of lines.
If a conflict is found,
.B merge
normally outputs a warning and brackets the conflict with
.B <<<<<<<
and
.B >>>>>>>
lines.
A typical conflict will look like this:
.LP
.RS
.nf
.BI <<<<<<< " file A"
.I "lines in file A"
.B "======="
.I "lines in file B"
.BI >>>>>>> " file B"
.RE
.fi
.LP
If there are conflicts, the user should edit the result and delete one of the
alternatives.
.SH OPTIONS
.TP
.B \-A
Output conflicts using the
.B \-A
style of
.BR diff3 (1),
if supported by
.BR diff3 .
This merges all changes leading from
.I file2
to
.I file3
into
.IR file1 ,
and is usually the best choice for merging.
This option is the default if
.B diff3
supports it.
.TP
\f3\-E\fP, \f3\-e\fP
These options specify conflict styles that generate less information
than
.BR \-A .
See
.BR diff3 (1)
for details.
If
.B diff3
does not support
.BR \-A ,
then
.B \-E
is the default if it is supported, and
.B \-e
is otherwise.
With
.BR \-e ,
.B merge
does not warn about conflicts.
.TP
.BI \-L " label"
This option may be given up to three times, and specifies labels
to be used in place of the corresponding file names in conflict reports.
That is,
.B "merge\ \-L\ x\ \-L\ y\ \-L\ z\ a\ b\ c"
generates output that looks like it came from files
.BR x ,
.B y
and
.B z
instead of from files
.BR a ,
.B b
and
.BR c .
.TP
.BI \-p
Send results to standard output instead of overwriting
.IR file1 .
.TP
.BI \-q
Quiet; do not warn about conflicts.
.BI \-V
Print \*r's version number.
.SH DIAGNOSTICS
Exit status is 0 for no conflicts, 1 for some conflicts, 2 for trouble.
.SH IDENTIFICATION
Author: Walter F. Tichy.
.br
Manual Page Revision: \*(Rv; Release Date: \*(Dt.
.br
Copyright \(co 1982, 1988, 1989 Walter F. Tichy.
.br
Copyright \(co 1990, 1991, 1992, 1993 Paul Eggert.
.SH SEE ALSO
diff3(1), diff(1), rcsmerge(1), co(1).