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

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.\" Written by: John H. Baldwin <jhb@FreeBSD.org>
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.Dd April 20, 2021
.Dt ETCUPDATE 8
.Os
.Sh NAME
.Nm etcupdate
.Nd "manage updates to system files not updated by installworld"
.Sh SYNOPSIS
.Nm
.Op Fl npBF
.Op Fl d Ar workdir
.Op Fl r | Fl s Ar source | Fl t Ar tarball
.Op Fl A Ar patterns
.Op Fl D Ar destdir
.Op Fl I Ar patterns
.Op Fl L Ar logfile
.Op Fl M Ar options
.Nm
.Cm build
.Op Fl B
.Op Fl d Ar workdir
.Op Fl s Ar source
.Op Fl L Ar logfile
.Op Fl M Ar options
.Ar tarball
.Nm
.Cm diff
.Op Fl d Ar workdir
.Op Fl D Ar destdir
.Op Fl I Ar patterns
.Op Fl L Ar logfile
.Nm
.Cm extract
.Op Fl B
.Op Fl d Ar workdir
.Op Fl s Ar source | Fl t Ar tarball
.Op Fl D Ar destdir
.Op Fl L Ar logfile
.Op Fl M Ar options
.Nm
.Cm resolve
.Op Fl p
.Op Fl d Ar workdir
.Op Fl D Ar destdir
.Op Fl L Ar logfile
.Nm
.Cm revert
.Op Fl d Ar workdir
.Op Fl D Ar destdir
.Op Fl L Ar logfile
.Ar
.Nm
.Cm status
.Op Fl d Ar workdir
.Op Fl D Ar destdir
.Sh DESCRIPTION
The
.Nm
utility is a tool for managing updates to files that are not updated as
part of
.Sq make installworld
such as files in
.Pa /etc .
It manages updates by doing a three-way merge of changes made to these
files against the local versions.
It is also designed to minimize the amount of user intervention with
the goal of simplifying upgrades for clusters of machines.
.Pp
To perform a three-way merge,
.Nm
keeps copies of the current and previous versions of files that it manages.
These copies are stored in two trees known as the
.Dq current
and
.Dq previous
trees.
During a merge,
.Nm
compares the
.Dq current
and
.Dq previous
copies of each file to determine which changes need to be merged into the
local version of each file.
If a file can be updated without generating a conflict,
.Nm
will update the file automatically.
If the local changes to a file conflict with the changes made to a file in
the source tree,
then a merge conflict is generated.
The conflict must be resolved after the merge has finished.
The
.Nm
utility will not perform a new merge until all conflicts from an earlier
merge are resolved.
.Sh MODES
The
.Nm
utility supports several modes of operation.
The mode is specified via an optional command argument.
If present, the command must be the first argument on the command line.
If a command is not specified, the default mode is used.
.Ss Default Mode
The default mode merges changes from the source tree to the destination
directory.
First,
it updates the
.Dq current
and
.Dq previous
trees.
Next,
it compares the two trees merging changes into the destination directory.
Finally,
it displays warnings for any conditions it could not handle automatically.
.Pp
If the
.Fl r
option is not specified,
then the first step taken is to update the
.Dq current
and
.Dq previous
trees.
If a
.Dq current
tree already exists,
then that tree is saved as the
.Dq previous
tree.
An older
.Dq previous
tree is removed if it exists.
By default the new
.Dq current
tree is built from a source tree.
However,
if a tarball is specified via the
.Fl t
option,
then the tree is extracted from that tarball instead.
.Pp
Next,
.Nm
compares the files in the
.Dq current
and
.Dq previous
trees.
If a file was removed from the
.Dq current
tree,
then it will be removed from the destination directory only if it
does not have any local modifications.
If a file was added to the
.Dq current
tree,
then it will be copied to the destination directory only if it
would not clobber an existing file.
If a file is changed in the
.Dq current
tree,
then
.Nm
will attempt to merge the changes into the version of the file in the
destination directory.
If the merge encounters conflicts,
then a version of the file with conflict markers will be saved for
future resolution.
If the merge does not encounter conflicts,
then the merged version of the file will be saved in the destination
directory.
If
.Nm
is not able to safely merge in changes to a file other than a merge conflict,
it will generate a warning.
.Pp
For each file that is updated a line will be output with a leading character
to indicate the action taken.
The possible actions follow:
.Pp
.Bl -tag -width "A" -compact -offset indent
.It A
Added
.It C
Conflict
.It D
Deleted
.It M
Merged
.It U
Updated
.El
.Pp
Finally,
if any warnings were encountered they are displayed after the merge has
completed.
.Pp
Note that for certain files
.Nm
will perform post-install actions any time that the file is updated.
Specifically,
.Xr pwd_mkdb 8
is invoked if
.Pa /etc/master.passwd
is changed,
.Xr cap_mkdb 1
is invoked to update
.Pa /etc/login.conf.db
if
.Pa /etc/login.conf
is changed,
.Xr newaliases 1
is invoked if
.Pa /etc/mail/aliases
is changed,
.Xr services_mkdb 8
is invoked if
.Pa /etc/services
is changed,
.Xr tzsetup 8
is invoked if
.Pa /etc/localtime
is changed and if
.Fa /var/db/zoneinfo
exists,
and
.Pa /etc/rc.d/motd
is invoked if
.Pa /etc/motd
is changed.
One exception is that if
.Pa /etc/mail/aliases
is changed and the destination directory is not the default,
then a warning will be issued instead.
This is due to a limitation of the
.Xr newaliases 1
command.
Similarly,
if
.Pa /etc/motd
is changed and the destination directory is not the default,
then
.Pa /etc/rc.d/motd
will not be executed due to a limitation of that script.
In this case no warning is issued as the result of
.Pa /etc/rc.d/motd
is merely cosmetic and will be corrected on the next reboot.
.Ss Build Mode
The
.Cm build
mode is used to build a tarball that contains a snapshot of a
.Dq current
tree.
This tarball can be used by the default and extract modes.
Using a tarball can allow
.Nm
to perform a merge without requiring a source tree that matches the
currently installed world.
The
.Fa tarball
argument specifies the name of the file to create.
The file will be a
.Xr tar 5
file compressed with
.Xr bzip2 1 .
.Ss Diff Mode
The
.Cm diff
mode compares the versions of files in the destination directory to the
.Dq current
tree and generates a unified format diff of the changes.
This can be used to determine which files have been locally modified and how.
Note that
.Nm
does not manage files that are not maintained in the source tree such as
.Pa /etc/fstab
and
.Pa /etc/rc.conf .
.Ss Extract Mode
The
.Cm extract
mode generates a new
.Dq current
tree.
Unlike the default mode,
it does not save any existing
.Dq current
tree and does not modify any existing
.Dq previous
tree.
The new
.Dq current
tree can either be built from a source tree or extracted from a tarball.
.Ss Resolve Mode
The
.Cm resolve
mode is used to resolve any conflicts encountered during a merge.
In this mode,
.Nm
iterates over any existing conflicts prompting the user for actions to take
on each conflicted file.
For each file, the following actions are available:
.Pp
.Bl -tag -width "(tf) theirs-full" -compact
.It (p)  postpone
Ignore this conflict for now.
.It (df) diff-full
Show all changes made to the merged file as a unified diff.
.It (e)  edit
Change the merged file in an editor.
.It (r)  resolved
Install the merged version of the file into the destination directory.
.It (mf) mine-full
Use the version of the file in the destination directory and ignore any
changes made to the file in the
.Dq current
tree.
.It (tf) theirs-full
Use the version of the file from the
.Dq current
tree and discard any local changes made to the file.
.It (h)  help
Display the list of commands.
.El
.Ss Revert Mode
The
.Cm revert
mode is used to restore the stock versions of files.
In this mode,
.Nm
installs the stock version of requested files.
This mode cannot be used to restore directories, only individual files.
.Ss Status Mode
The
.Cm status
mode shows a summary of the results of the most recent merge.
First it lists any files for which there are unresolved conflicts.
Next it lists any warnings generated during the last merge.
If the last merge did not generate any conflicts or warnings,
then nothing will be output.
.Sh OPTIONS
The following options are available.
Note that most options do not apply to all modes.
.Bl -tag -width ".Fl A Ar patterns"
.It Fl A Ar patterns
Always install the new version of any files that match any of the patterns
listed in
.Ar patterns .
Each pattern is evaluated as an
.Xr sh 1
shell pattern.
This option may be specified multiple times to specify multiple patterns.
Multiple space-separated patterns may also be specified in a single
option.
Note that ignored files specified via the
.Ev IGNORE_FILES
variable or the
.Fl I
option will not be installed.
.It Fl B
Do not build generated files in a private object tree.
Instead,
reuse the generated files from a previously built object tree that matches
the source tree.
This can be useful to avoid gratuitous conflicts in
.Xr sendmail 8
configuration
files when bootstrapping.
It can also be useful for building a tarball that matches a specific
world build.
.It Fl D Ar destdir
Specify an alternate destination directory as the target of a merge.
This is analogous to the
.Dv DESTDIR
variable used with
.Sq make installworld .
The default destination directory is an empty string which results in
merges updating
.Pa /etc
on the local machine.
.It Fl d Ar workdir
Specify an alternate directory to use as the work directory.
The work directory is used to store the
.Dq current
and
.Dq previous
trees as well as unresolved conflicts.
The default work directory is
.Pa <destdir>/var/db/etcupdate .
.It Fl F
Ignore changes in the FreeBSD ID string when comparing files in the
destination directory to files in either of the
.Dq current
or
.Dq previous
trees.
In
.Cm diff
mode,
this reduces noise due to FreeBSD ID string changes in the output.
During an update this can simplify handling for harmless conflicts caused
by FreeBSD ID string changes.
.Pp
Specifically,
if a file in the destination directory is identical to the same file in the
.Dq previous
tree modulo the FreeBSD ID string,
then the file is treated as if it was unmodified and the
.Dq current
version of the file will be installed.
Similarly,
if a file in the destination directory is identical to the same file in the
.Dq current
tree modulo the FreeBSD ID string,
then the
.Dq current
version of the file will be installed to update the ID string.
If the
.Dq previous
and
.Dq current
versions of the file are identical,
then
.Nm
will not change the file in the destination directory.
.Pp
Due to limitations in the
.Xr diff 1
command,
this option may not have an effect if there are other changes in a file that
are close to the FreeBSD ID string.
.It Fl I Ar patterns
Ignore any files that match any of the patterns listed in
.Ar patterns .
No warnings or other messages will be generated for those files during a
merge.
Each pattern is evaluated as an
.Xr sh 1
shell pattern.
This option may be specified multiple times to specify multiple patterns.
Multiple space-separated patterns may also be specified in a single
option.
.It Fl L Ar logfile
Specify an alternate path for the log file.
The
.Nm
utility logs each command that it invokes along with the standard output
and standard error to this file.
By default the log file is stored in a file named
.Pa log
in the work directory.
.It Fl M Ar options
Pass
.Ar options
as additional parameters to
.Xr make 1
when building a
.Dq current
tree.
This can be used for to set the
.Dv TARGET
or
.Dv TARGET_ARCH
variables for a cross-build.
.It Fl n
Enable
.Dq dry-run
mode.
Do not merge any changes to the destination directory.
Instead,
report what actions would be taken during a merge.
Note that the existing
.Dq current
and
.Dq previous
trees will not be changed.
If the
.Fl r
option is not specified,
then a temporary
.Dq current
tree will be extracted to perform the comparison.
.It Fl p
Enable
.Dq pre-world
mode.
Only merge changes to files that are necessary to successfully run
.Sq make installworld
or
.Sq make installkernel .
When this flag is enabled,
the existing
.Dq current
and
.Dq previous
trees are left alone.
Instead,
a temporary tree is populated with the necessary files.
This temporary tree is compared against the
.Dq current
tree.
This allows a normal update to be run after
.Sq make installworld
has completed.
Any conflicts generated during a
.Dq pre-world
update should be resolved by a
.Dq pre-world
.Cm resolve .
.It Fl r
Do not update the
.Dq current
and
.Dq previous
trees during a merge.
This can be used to
.Dq re-run
a previous merge operation.
.It Fl s Ar source
Specify an alternate source tree to use when building or extracting a
.Dq current
tree.
The default source tree is
.Pa /usr/src .
.It Fl t Ar tarball
Extract a new
.Dq current
tree from a tarball previously generated by the
.Cm build
command rather than building the tree from a source tree.
.El
.Sh CONFIG FILE
The
.Nm
utility can also be configured by setting variables in an optional
configuration file named
.Pa /etc/etcupdate.conf .
Note that command line options override settings in the configuration file.
The configuration file is executed by
.Xr sh 1 ,
so it uses that syntax to set configuration variables.
The following variables can be set:
.Bl -tag -width ".Ev ALWAYS_INSTALL"
.It Ev ALWAYS_INSTALL
Always install files that match any of the patterns listed in this variable
similar to the
.Fl A
option.
.It Ev DESTDIR
Specify an alternate destination directory similar to the
.Fl D
option.
.It Ev EDITOR
Specify a program to edit merge conflicts.
.It Ev FREEBSD_ID
Ignore changes in the FreeBSD ID string similar to the
.Fl F
option.
This is enabled by setting the variable to a non-empty value.
.It Ev IGNORE_FILES
Ignore files that match any of the patterns listed in this variable
similar to the
.Fl I
option.
.It Ev LOGFILE
Specify an alternate path for the log file similar to the
.Fl L
option.
.It Ev MAKE_OPTIONS
Pass additional options to
.Xr make 1
when building a
.Dq current
tree similar to the
.Fl M
option.
.It Ev SRCDIR
Specify an alternate source tree similar to the
.Fl s
option.
.It Ev WORKDIR
Specify an alternate work directory similar to the
.Fl d
option.
.El
.Sh ENVIRONMENT
The
.Nm
utility uses the program identified in the
.Ev EDITOR
environment variable to edit merge conflicts.
If
.Ev EDITOR
is not set,
.Xr vi 1
is used as the default editor.
.Sh FILES
.Bl -tag -width ".Pa /var/db/etcupdate/log" -compact
.It Pa /etc/etcupdate.conf
Optional config file.
.It Pa /var/db/etcupdate
Default work directory used to store trees and other data.
.It Pa /var/db/etcupdate/log
Default log file.
.El
.Sh EXIT STATUS
.Ex -std
.Sh EXAMPLES
To compare the files in
.Pa /etc
with the stock versions:
.Pp
.Dl "etcupdate diff"
.Pp
To merge changes after an upgrade via the buildworld and installworld process:
.Pp
.Dl "etcupdate"
.Pp
To resolve any conflicts generated during a merge:
.Pp
.Dl "etcupdate resolve"
.Ss Bootstrapping
The
.Nm
utility may need to be bootstrapped before it can be used.
The
.Cm diff
command will fail with an error about a missing reference tree if
bootstrapping is needed.
.Pp
Bootstrapping
.Nm
requires a source tree that matches the currently installed world.
The easiest way to ensure this is to bootstrap
.Nm
before updating the source tree to start the next world upgrade cycle.
First,
generate a reference tree:
.Pp
.Dl "etcupdate extract"
.Pp
Second,
use the
.Cm diff
command to compare the reference tree to your current files in
.Pa /etc .
Undesired differences should be removed using an editor,
.Xr patch 1 ,
or by copying files from the reference tree
.Po
located at
.Pa /var/db/etcupdate/current
by default
.Pc
.
.Pp
If the tree at
.Pa /usr/src
is already newer than the currently installed world,
a new tree matching the currently installed world can be checked out to
a temporary location.
The reference tree for
.Nm
can then be generated via:
.Pp
.Dl "etcupdate extract -s /path/to/tree"
.Pp
The
.Cm diff
command can be used as above to remove undesired differences.
Afterwards,
the changes in the tree at
.Pa /usr/src
can be merged via a regular merge.
.Sh DIAGNOSTICS
The following warning messages may be generated during a merge.
Note that several of these warnings cover obscure cases that should occur
rarely if at all in practice.
For example,
if a file changes from a file to a directory in the
.Dq current
tree
and the file was modified in the destination directory,
then a warning will be triggered.
In general,
when a warning references a pathname,
the corresponding file in the destination directory is not changed by a
merge operation.
.Bl -diag
.It "Directory mismatch: <path> (<type>)"
An attempt was made to create a directory at
.Pa path
but an existing file of type
.Dq type
already exists for that path name.
.It "Modified link changed: <file> (<old> became <new>)"
The target of a symbolic link named
.Pa file
was changed from
.Dq old
to
.Dq new
in the
.Dq current
tree.
The symbolic link has been modified to point to a target that is neither
.Dq old
nor
.Dq new
in the destination directory.
.It "Modified mismatch: <file> (<new> vs <dest>)"
A file named
.Pa file
of type
.Dq new
was modified in the
.Dq current
tree,
but the file exists as a different type
.Dq dest
in the destination directory.
.It "Modified <type> changed: <file> (<old> became <new>)"
A file named
.Pa file
changed type from
.Dq old
in the
.Dq previous
tree to type
.Dq new
in the
.Dq current
tree.
The file in the destination directory of type
.Dq type
has been modified,
so it could not be merged automatically.
.It "Modified <type> remains: <file>"
The file of type
.Dq type
named
.Pa file
has been removed from the
.Dq current
tree,
but it has been locally modified.
The modified version of the file remains in the destination directory.
.It "Needs update: /etc/localtime (required manual update via tzsetup(8))"
The
.Fa /var/db/zoneinfo
file does not exist,
so
.Nm
was not able to refresh
.Fa /etc/localtime
from its source file in
.Fa /usr/share/zoneinfo .
Running
.Xr tzsetup 8
will both refresh
.Fa /etc/localtime
and generate
.Fa /var/db/zoneinfo
permitting future updates to refresh
.Fa /etc/localtime
automatically.
.It "Needs update: /etc/mail/aliases.db (required manual update via newaliases(1))"
The file
.Pa /etc/mail/aliases
was updated during a merge with a non-empty destination directory.
Due to a limitation of the
.Xr newaliases 1
command,
.Nm
was not able to automatically update the corresponding aliases database.
.It "New file mismatch: <file> (<new> vs <dest>)"
A new file named
.Pa file
of type
.Dq new
has been added to the
.Dq current
tree.
A file of that name already exists in the destination directory,
but it is of a different type
.Dq dest .
.It "New link conflict: <file> (<new> vs <dest>)"
A symbolic link named
.Pa file
has been added to the
.Dq current
tree that links to
.Dq new .
A symbolic link of the same name already exists in the destination
directory,
but it links to a different target
.Dq dest .
.It "Non-empty directory remains: <file>"
The directory
.Pa file
was removed from the
.Dq current
tree,
but it contains additional files in the destination directory.
These additional files as well as the directory remain.
.It "Remove mismatch: <file> (<old> became <new>)"
A file named
.Pa file
changed from type
.Dq old
in the
.Dq previous
tree to type
.Dq new
in the
.Dq current
tree,
but it has been removed in the destination directory.
.It "Removed file changed: <file>"
A file named
.Pa file
was modified in the
.Dq current
tree,
but it has been removed in the destination directory.
.It "Removed link changed: <file> (<old> became <new>)"
The target of a symbolic link named
.Pa file
was changed from
.Dq old
to
.Dq new
in the
.Dq current
tree,
but it has been removed in the destination directory.
.El
.Sh SEE ALSO
.Xr cap_mkdb 1 ,
.Xr diff 1 ,
.Xr make 1 ,
.Xr newaliases 1 ,
.Xr sh 1 ,
.Xr mergemaster 8 ,
.Xr pwd_mkdb 8 ,
.Xr services_mkdb 8 ,
.Xr tzsetup 8
.Sh HISTORY
The
.Nm
utility first appeared in
.Fx 10.0 .
.Sh AUTHORS
The
.Nm
utility was written by
.An John Baldwin Aq Mt jhb@FreeBSD.org .
.Sh BUGS
Rerunning a merge does not automatically delete conflicts left over from a
previous merge.
Any conflicts must be resolved before the merge can be rerun.
It is not clear if this is a feature or a bug.
.Pp
There is no way to easily automate conflict resolution for specific files.
For example, one can imagine a syntax along the lines of
.Pp
.Dl "etcupdate resolve tf /some/file"
.Pp
to resolve a specific conflict in an automated fashion.
.Pp
Bootstrapping
.Nm
often results in gratuitous diffs in
.Pa /etc/mail/*.cf
that cause conflicts in the first merge.
If an object tree that matches the source tree is present when bootstrapping,
then passing the
.Fl B
flag to the
.Cm extract
command can work around this.