freebsd-src/usr.sbin/mergemaster/mergemaster.8

.\" Copyright (c) 1998-2011 Douglas Barton
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.Dd May 20, 2021
.Dt MERGEMASTER 8
.Os
.Sh NAME
.Nm mergemaster
.Nd merge configuration files, et al during an upgrade
.Sh SYNOPSIS
.Nm
.Op Fl scrvhpCP
.Op Fl a|iFU
.Op Fl -run-updates=[always|never]
.Op Fl m Ar /path/to/sources
.Op Fl t Ar /path/to/temp/root
.Op Fl d
.Op Fl u Ar N
.Op Fl w Ar N
.Op Fl A Ar Target architecture
.Op Fl D Ar /destdir/path
.Sh DESCRIPTION
The
.Nm
utility is a Bourne shell script which is designed to aid you
in updating the various configuration and other files
associated with
.Fx .
It is
.Sy HIGHLY
recommended that you back up your
.Pa /etc
directory before beginning this process.
.Pp
The script uses
.Pa /usr/src/Makefile
to build a temporary root environment from
.Pa /
down, populating that environment with the various
files.
You can specify a different source directory
with the
.Fl m
command line option, or specify the destination
directory with the
.Fl D
option.
It then compares each file in that environment
to its installed counterpart.
When the script finds a
change in the new file, or there is no installed
version of the new file it gives you four options to
deal with it.
You can install the new file as is,
delete the new file, merge the old and new
files (as appropriate) using
.Xr sdiff 1
or leave the file in the temporary root environment to
merge by hand later.
.Pp
By default it creates the temporary root in
.Pa /var/tmp/temproot
and compares the
Version Control System (VCS) Id strings ($FreeBSD)
for files that have them, deleting
the temporary file if the strings match.
If there is
no Id string, or if the strings are different it
compares the files themselves.
You can
also specify that the script ignore the Id strings and
compare every file with the
.Fl s
option.
Using the
.Fl F
option
.Nm
will install the new file for you if they differ only by
VCS strings.
.Pp
The merge menu option is designed to let you easily combine your
customizations from the old version of a file into the new one.
While you can use the merge function to incorporate changes from
files that you have not customized,
it is not recommended.
.Pp
The
.Nm
utility checks your umask and issues a warning for anything
other than 022.
While it is not mandatory to grant
world read permissions for most configuration files, you
may run into problems without them.
If you choose a
umask other than 022 and experience trouble later this
could be the cause.
.Pa /etc/master.passwd
is treated as a special case.
If you choose to install
this file or a merged version of it the file permissions
are always 600 (rw-------) for security reasons.
After
installing an updated version of this file you should
probably run
.Xr pwd_mkdb 8
with the
.Fl p
option to rebuild your password databases
and recreate
.Pa /etc/passwd .
.Pp
The script uses the owner and group ids
that the files are created with by
.Pa /usr/src/etc/Makefile ,
and file permissions as specified by the umask.
Unified diffs are used by default to display any
differences unless you choose context diffs.
.Pp
The
.Nm
utility will source scripts that you specify right before
it starts the comparison, and after it is done running.
The easiest way to handle this is to place the path
to the script(s) in the appropriate variables in your
.Pa .mergemasterrc
file.
The script sourced before comparison is named in
.Ev MM_PRE_COMPARE_SCRIPT ,
and the one sourced after the script is done is
.Ev MM_EXIT_SCRIPT .
This is the recommended way to specify local modifications,
or files that you want to give special handling to.
This includes files that you want to be deleted without
being compared.
Because the named scripts are sourced from within
.Nm ,
all of the script's variables are available for use in
your custom script.
You can also use
.Pa /etc/mergemaster.rc
which will be read before
.Pa .mergemasterrc .
Options specified on the command line are updated last,
and therefore can override both files.
.Pp
When the comparison is done if there are any files remaining
in the temproot directory they will be listed, and if the
.Fl a
option is not in use the user will be given the option of
deleting the temproot directory.
If there are no files remaining in the temproot directory
it will be deleted.
.Pp
The options are as follows:
.Bl -tag -width Fl
.It Fl s
Perform a strict comparison, diffing every pair of files.
This comparison is performed line by line,
without regard to VCS Ids.
.It Fl c
Use context diffs instead of unified diffs.
.It Fl r
Re-run
.Nm
on a previously cleaned directory, skipping the creation of
the temporary root environment.
This option is compatible
with all other options.
.It Fl v
Be more verbose about the process.
You should probably use
this option the first time you run
.Nm .
This option also gives you a list of files that exist
only in the installed version of
.Pa /etc .
.It Fl a
Run automatically.
This option will leave all the files that
differ from the installed versions in the temporary directory
to be dealt with by hand.
If the
.Pa temproot
directory exists, it creates a new one in a previously
non-existent directory.
This option unsets the verbose flag,
and is not compatible with
.Fl i ,
.Fl F ,
or
.Fl U .
Setting
.Fl a
makes
.Fl w
superfluous.
.It Fl h
Display usage and help information.
.It Fl i
Automatically install any files that do not exist in the
destination directory.
.It Fl p
Pre-buildworld mode.
Compares only files known to be essential to the success of
{build|install}world, i.e.,
.Pa /etc/group
and
.Pa /etc/master.passwd .
.It Fl F
If the files differ only by VCS Id ($FreeBSD)
install the new file.
.It Fl C
After a standard
.Nm
run,
compares your rc.conf[.local] options to the defaults.
.It Fl P
Preserve files that you replace in
.Pa /var/tmp/mergemaster/preserved-files-<date> ,
or another directory you specify in your
.Nm
rc file.
.It Fl U
Attempt to auto upgrade files that have not been user modified.
This option can be dangerous when there are critical changes
in the new versions that affect your running system.
.It Fl -run-updates=[always|never]
Specify always or never to run newaliases, pwd_mkdb, etc.
at the end of the comparison run.
If this option is omitted the default is to prompt the user
for each update as necessary.
.It Fl m Ar /path/to/sources
Specify the path to the directory where you want to do the
.Xr make 1 .
(In other words, where your sources are, but -s was already
taken.)
In older versions of
.Nm
the path to
.Pa src/etc
was required.
.Nm
will convert the path if this older method is used.
.It Fl t Ar /path/to/temp/root
Create the temporary root environment in
.Pa /path/to/temp/root
instead of the default
.Pa /var/tmp/temproot .
.It Fl d
Add the date and time to the name of the temporary
root directory.
If
.Fl t
is specified, this option must
follow it if you want the date added too.
.It Fl u Ar N
Specify a numeric umask.
The default is 022.
.It Fl w Ar N
Supply an alternate screen width to the
.Xr sdiff 1
command in numbers of columns.
The default is 80.
.It Fl A Ar Target architecture
Specify an alternative
.Ev TARGET_ARCH
architecture name.
.It Fl D Ar /path
Specify the destination directory for the installed files.
.El
.Sh ENVIRONMENT
The
.Nm
utility uses the
.Ev PAGER
environment variable if set.
Otherwise it uses
.Xr less 1 .
If
.Ev PAGER
specifies a program outside
its
limited
.Ev PATH
without specifying the full path,
.Nm
prompts you with options on how to proceed.
The
.Ev MM_PRE_COMPARE_SCRIPT
and
.Ev MM_EXIT_SCRIPT
variables are used as described above.
Other variables that are used by the script internally
can be specified in
.Pa .mergemasterrc
as described in more detail below.
.Sh FILES
.Bl -tag -width $HOME/.mergemasterrc -compact
.It Pa /etc/mergemaster.rc
.It Pa $HOME/.mergemasterrc
.El
.Pp
The
.Nm
utility will
.Ic .\&
(source) these files if they exist.
Command line options
will override rc file options.
.Pa $HOME/.mergemasterrc
overrides
.Pa /etc/mergemaster.rc .
Here is an example
with all values commented out:
.Bd -literal
# These are options for mergemaster, with their default values listed
# The following options have command line overrides
#
# The target architecture (-A, unset by default)
#ARCHSTRING='TARGET_ARCH=<foo>'
#
# Sourcedir is the directory to do the 'make' in (-m)
#SOURCEDIR='/usr/src'
#
# Directory to install the temporary root environment into (-t)
#TEMPROOT='/var/tmp/temproot'
#
# Specify the destination directory for the installed files (-D)
#DESTDIR=
#
# Strict comparison skips the VCS Id test and compares every file (-s)
#STRICT=no
#
# Type of diff, such as unified, context, etc. (-c)
#DIFF_FLAG='-u'
#
# Install the new file if it differs only by VCS Id ($FreeBSD, -F)
#FREEBSD_ID=
#
# Verbose mode includes more details and additional checks (-v)
#VERBOSE=
#
# Automatically install files that do not exist on the system already (-i)
#AUTO_INSTALL=
#
# Automatically upgrade files that have not been user modified (-U)
# ***DANGEROUS***
#AUTO_UPGRADE=
#
# Either always or never run newaliases, pwd_mkdb at the end (--run-updates)
#RUN_UPDATES=
#
# Compare /etc/rc.conf[.local] to /etc/defaults/rc.conf (-C)
#COMP_CONFS=
#
# Preserve files that you replace (-P)
#PRESERVE_FILES=
#PRESERVE_FILES_DIR=/var/tmp/mergemaster/preserved-files-`date +%y%m%d-%H%M%S`
#
# The umask for mergemaster to compare the default file's modes to (-u)
#NEW_UMASK=022
#
# The following options have no command line overrides
#
# Files to always avoid comparing
#IGNORE_FILES='/etc/motd /etc/printcap foo bar'
#
# Additional options for diff.  This will get unset when using -s.
#DIFF_OPTIONS='-Bb'	# Ignore changes in whitespace
#
# Location to store the list of mtree values for AUTO_UPGRADE purposes
#MTREEDB='/var/db'
#
# For those who just cannot stand including the full path to PAGER
#DONT_CHECK_PAGER=
#
# If you set 'yes' above, make sure to include the PATH to your pager
#PATH=/bin:/usr/bin:/usr/sbin
#
# Delete stale files in /etc/rc.d without prompting
#DELETE_STALE_RC_FILES=
#
# Specify the path to scripts to run before the comparison starts,
# and/or after the script has finished its work
#MM_PRE_COMPARE_SCRIPT=
#MM_EXIT_SCRIPT=
.Ed
.Sh EXIT STATUS
Exit status is 0 on successful completion, or if the user bails out
manually at some point during execution.
.Pp
Exit status is 1 if it fails for one of the following reasons:
.Pp
Invalid command line option
.Pp
Failure to create the temporary root environment
.Pp
Failure to populate the temporary root
.Pp
Presence of the 'nodev' option in
.Pa <DESTDIR>/etc/fstab
.Pp
Failure to install a file
.Sh EXAMPLES
Typically all you will need to do is type
.Nm
at the prompt and the script will do all the work for you.
.Pp
To use context diffs and have
.Nm
explain more things as it goes along, use:
.Pp
.Dl # mergemaster -cv
.Pp
To specify that
.Nm
put the temporary root environment in
.Pa /usr/tmp/root ,
use:
.Pp
.Dl # mergemaster -t /usr/tmp/root
.Pp
To specify a 110 column screen with a strict
comparison, use:
.Pp
.Dl # mergemaster -sw 110
.Sh SEE ALSO
.Xr diff 1 ,
.Xr make 1 ,
.Xr less 1 ,
.Xr sdiff 1 ,
.Xr etcupdate 8 ,
.Xr pwd_mkdb 8
.Pp
.Pa /usr/src/etc/Makefile
.Rs
.%U https://docs.freebsd.org/en/books/handbook/cutting-edge/#makeworld
.%T The FreeBSD Handbook
.Re
.Sh HISTORY
The
.Nm
utility was first publicly available on one of my
web pages in a much simpler form under the name
.Pa comproot
on 13 March 1998.
The idea for creating the
temporary root environment comes from Nik Clayton's
make world tutorial which is referenced above.
.Sh AUTHORS
This manual page and the script itself were written by
.An Douglas Barton Aq Mt dougb@FreeBSD.org .