Provided by: fhist_1.18-2_amd64 
NAME
fmerge - merge files
SYNOPSIS
fmerge [ option... ] basefile fileA fileB
fmerge -Help
fmerge -VERSion
DESCRIPTION
The fmerge program is used to compare the changes between two different descendants of a base file, and
creates an output file which contains both sets of changes. This is useful when two users both take the
same version of a file and make independent edits to it, and then later want to create a file which
contains both sets of edits. In such a use, the original file that both sets of edits is derived from is
called the base file. The two files containing the edits are called file A and file B.
The command:
fmerge basefile fileA fileB -o outputfile
produces the output file which contains the edits contained in file A and file B, based on the base file
. If the -Output option was not used, or if no outputfile is specified, then the merged lines are typed
to the standard output. The order of specifying file A and file B is usually unimportant.
The fmerge program can also be used to remove earlier edits made to a module. To do this, make the
version containing the edits you want to delete be the basefile. Make the version previous to the edit
you want deleted be file A. Finally, make the most recent version of the file which contains the other
edits (including the one you want deleted) be file B. Then the result of merging will be the newest
version of the module minus the changes made by the edit you wanted removed. For example, if three
successive versions of some module have the names edit10, edit11 and edit12, and you want the changes
done by edit11 to be undone, but still want the changes done by edit12, then you use the command:
fmerge edit11 edit10 edit12 -o outputfile
While merging the two sets of edits, fmerge may discover conflicts. A conflict occurs when the same line
of the base file is changed by both of the two sets of edits. The change can be due to new lines being
inserted, lines being deleted, or both. When conflicts occur, the output file contains conflict
identification lines, which are lines containing the string '/−/−/−/'. These lines indicate the region
where the two sets of edits are incompatible. You must then edit the output file and remove these lines,
and in addition correct the conflicts manually in order to produce the correct result.
OPTIONS
The following options are understood:
-Conflicts [ conflictfile ]
Since conflicts due to deletions are invisible in the output file, and inserts do not specify
which of the two edits inserted the lines, there is an alternative output format from the fmerge
program. This output format describes what happens to each line of the base file, so that
conflicts are easier to detect and fix. The command:
fmerge basefile fileA fileB -c conflictfile
produces the file describing the results of the merge in detail. If the -Conflicts option is
specified without any conflictfile name, then the conflicts are send to the standard output.
If there are conflicts, and the -Conflicts options is not specified, the fmerge program will exit
with a status of 1.
The conflict file contains lines which contain three characters and then some text. The first
three characters describe what is happening to the base file at that point. These characters are
the following:
IA This line was inserted by file A.
DA This line was deleted by file A.
IB This line was inserted by file B.
DB This line was deleted by file B.
<blanks>
This line is unchanged.
X This is a conflict identification line.
U There are unspecified unchanged lines here.
Each set of conflicts is flagged by three identification lines. The first line indicates the
beginning of the conflict, and specifies the line numbers for the base file and two divergent
files. The second conflict identification line separates lines changed by file A from lines
changed by file B. The third conflict identification indicates the end of the conflict.
You can edit this conflict file to remove the conflicts. This involves deleting the conflict
identification lines, and changing the conflicting lines as necessary to fix the conflict. While
doing this, remember to leave three blank characters at the front of any new lines you insert
while correcting the conflicts. When you are done, there should be no lines which begin with an
'X' in the file. All other lines can remain. Then you can use the command:
fmerge conflictfile -o outputfile
to create the new output file which has the desired data. Once again, if no -Output option or
outputfile is used, the output is send to the standard output.
-Unchanged number
Besides physical conflicts, there can be logical conflicts. These are changes made to different
lines in the base file such that the program is no longer correct. Such conflicts cannot be
detected by a program, and so these must be checked manually. In order to make this process
easier, the -Unchanged option can be used to reduce the size of the conflict file to only include
regions near changed lines. This file can then be examined in order to detect possible logical
conflicts. As an example, the command:
fmerge basefile fileA fileB -c -u 3
will send to the standard output all changes made by either sets of edits, with only three
unchanged lines surrounding each edit.
When using the -Unchanged option, the conflict file will contain lines starting with 'U'. These
represent unchanged lines, and the number following the letter is the number of unchanged lines.
The resulting conflict file cannot be read to produce an output file because of the missing
lines. If this is attempted, an error will be generated.
It is possible to use both -Output and -Conflicts in the same command. Thus you can produce the
output file which you hope is correct, and also produce the conflict file which you can use to
check for logical conflicts.
-Verbose [ number ]
This option can be specified with any other action, and outputs status information about the
progress of the action. This is useful for debugging of problems, or just for amusement when the
system is slow or a large file is being processed. It accepts a numeric argument to indicate the
verbosity for output. The levels are as follows:
0 No output at all (except for errors).
1 Single‐line output describing action (default).
2 Detailed status as action proceeds.
-Failures number
This option restricts the number of physical conflicts that are allowed before failing. This is
used if you are not interested in the results if there are too many conflicts.
-Help
Give some help on how to use the fmerge program.
-Ignore
Ignore all conflicts.
-Ignore_Identical_Conflicts
The option may be used to suppress conflicts which make identical deletes, or identical inserts,
or identical changes. This is often desirable when merging two source code branches.
-VERSion
Show what version of fmerge is running.
All options may be abbreviated; the abbreviation is documented as the upper case letters, all lower case
letters and underscores (_) are optional. You must use consecutive sequences of optional letters.
All options are case insensitive, you may type them in upper case or lower case or a combination of both,
case is not important.
For example: the arguments "-help, "-HELP" and "-h" are all interpreted to mean the -Help option. The
argument "-hlp" will not be understood, because consecutive optional characters were not supplied.
Options and other command line arguments may be mixed arbitrarily on the command line.
The GNU long option names are understood. Since all option names for fmerge are long, this means
ignoring the extra leading '-'. The "-option=value" convention is also understood.
FILE NAME EXPANSION
As a convenience, if a pathname begins with a period and a environment variable exists with that name,
then the value of the environment variable will be used as the actual pathname. For example, if a
environment variable of .FOO has the value this.is.a.long.name, then the command
fmerge -o .FOO
is actually equivilant to the command
fmerge -o this.is.a.long.name
If you want to prevent the expansion of a pathname which begins with a period, then you can use an
alternate form for the pathname, as in:
fmerge -o ./.FOO
BINARY FILES
In general, fmerge can handle all text files you throw at it, even international text with unusual
encodings. However, fmerge is unable to cope elegantly with files which contain the NUL character.
The fcomp(1) program simply prints a warning, and continues, you need to know that it converts NUL
characters into an 0x80 value before performing the comparison.
The fmerge(1) program also converts the NUL character to an 0x80 value before merging, after a warning,
and any output file will contain this value, rather than the original NUL character.
The fhist(1) program, however, generates a fatal error if any input file contains NUL characters. This
is intended to protect your source files for unintentional corruption. Use -BINary for files which
absolutely must contain NUL characters.
EXIT STATUS
The fmerge program will exit with a status of 1 on any error. The fmerge program will only exit with a
status of 0 if there are no errors.
REFERENCES
This program is based on the algorithm in
An O(ND) Difference Algorithm and Its Variations, Eugene W. Myers, TR 85‐6, 10‐April‐1985,
Department of Computer Science, The University of Arizona, Tuscon, Arizona 85721.
See also:
A File Comparison Program, Webb Miller and Eugene W. Myers, Software Practice and Experience,
Volume 15, No. 11, November 1985.
COPYRIGHT
fmerge version 1.18.D001
Copyright (C) 1991, 1992, 1993, 1994, 1995, 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005,
2006, 2008, 2009 Peter Miller;
This program is derived from a work
Copyright (C) 1990 David I. Bell.
This program is free software; you can redistribute it and/or modify it under the terms of the GNU
General Public License as published by the Free Software Foundation; either version 3 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even
the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public
License for more details.
You should have received a copy of the GNU General Public License along with this program. If not, see
<http://www.gnu.org/licenses/>.
AUTHORS
Peter Miller Web: http://miller.emu.id.au/pmiller/ /\/\* E‐Mail: pmiller@opensource.org.au David I. Bell Web: http://www.canb.auug.org.au/~dbell E‐Mail: dbell@canb.auug.org.au