From 32322960234c8ec91e0d42835a3ec5ee63305070 Mon Sep 17 00:00:00 2001 From: Daniel Baumann Date: Sat, 2 Feb 2019 11:00:00 +0100 Subject: Adding upstream version 20190202. Signed-off-by: Daniel Baumann --- system-boot/manpages/en/persistence.conf.5 | 206 +++++++++++++++++++++++++++++ 1 file changed, 206 insertions(+) create mode 100644 system-boot/manpages/en/persistence.conf.5 (limited to 'system-boot/manpages/en/persistence.conf.5') diff --git a/system-boot/manpages/en/persistence.conf.5 b/system-boot/manpages/en/persistence.conf.5 new file mode 100644 index 0000000..834cb29 --- /dev/null +++ b/system-boot/manpages/en/persistence.conf.5 @@ -0,0 +1,206 @@ +.TH LIVE\-BOOT conf 2015\-09\-22 5.0~a5-1 "Live Systems Project" + +.SH NAME +\fBpersistence.conf\fR \- Configuration file for persistence media in +live\-boot + +.SH DESCRIPTION +If live-boot probes a persistence volume with the label (or GPT name, +or file name, but from now on we will just say "label") "persistence", +that volume's persistence is fully customizable through the +\fBpersistence.conf\fR file stored on the root of its file system. Any such +labeled volume must have such a file, or it will be ignored. +.PP +The format of \fBpersistence.conf\fR allows empty lines and lines starting +with a "#" (used for comments), both which will be ignored. A so +called "custom mount" has the format: +.PP +.RS +\fIDIR\fR [\fIOPTION\fR]... +.RE +.PP +which roughly translates to "make \fIDIR\fR persistence in the way +described by the list of \fIOPTION\fRs". +.PP +For each custom mount \fIDIR\fR must be an absolute path that cannot +contain white spaces or the special . and .. path components, and +cannot be /live (or any of its sub-directories). +Once activated all changes (file +deletion, creation and modification) to \fIDIR\fR on the live file +system are stored persistently into a path equivalent to \fIDIR\fR on +the persistence media, called the source directory. The default way to +achieve persistence is to simply bind-mount the corresponding source +directory to \fIDIR\fR, but this can be changed through the use of +\fIOPTION\fRs. +.PP +All custom mounts will be done in an order so that no two custom +mounts can "hide" each other. For instance, if we have the two +\fIDIR\fR:s /a and /a/b it would always be the case that /a is mounted +first, then /a/b. This remains true no matter how the lines in +\fBpersistence.conf\fR are ordered, or if several \fBpersistence.conf\fR files +on different persistence media are used at the same time. However, it +is forbidden for custom mounts to have their source directory inside +the source directory of another custom mount, so the source +directories that are auto-created by live-boot does not support +"nested" mounts like /a and /a/b on the same media. In this case you +must use the \fBsource\fR option (see below) to make sure that they +are stored in different source directories. +.PP +When a source directory doesn't exist on the persistence media for a +certain custom mount, it will be created automatically, and +permissions and ownership will be optimistically set according to +\fIDIR\fR. It will also be bootstrapped by copying the contents of the +\fIDIR\fR into its source directory on the persistence media. The +bootstrapping will not happen when the \fBlink\fR or \fBunion\fR +options are used (see below). + +.SH OPTIONS +Custom mounts defined in \fBpersistence.conf\fR accept the following +options in a comma-separated list: +.IP "\fBsource\fR=\fIPATH\fR" 4 +When given, store the persistence changes into \fIPATH\fR on the +persistence media. \fIPATH\fR must be a relative path (with respect to the +persistence media root) that cannot contain white spaces or the +special . or .. path components, with the exception that it can be +just . which means the persistence media root. This option is mostly +relevant if you want to nest custom mounts, which otherwise would +cause errors, or if you want to make the whole media root available +(similar to the now deprecated \fBhome-rw\fR type of persistence). +.PP +The following options are mutually exclusive (only the last given one +will be in effect): +.IP "\fBbind\fR" 4 +Bind-mount the source directory to \fIDIR\fR. This is the default. +.IP "\fBlink\fR" 4 +Create the directory structure of the source directory on the +persistence media in \fIDIR\fR and create symbolic links from the +corresponding place in \fIDIR\fR to each file in the source directory. +Existing files or directories with the same name as any link will be +overwritten. Note that deleting the links in \fIDIR\fR will only +remove the link, not the corresponding file in the source; removed +links will reappear after a reboot. To permanently add or delete a +file one must do so directly in the source directory. +.IP +Effectively \fBlink\fR will make only files already in the source +directory persistent, not any other files in \fIDIR\fR. These files +must be manually added to the source directory to make use of this +option, and they will appear in \fIDIR\fR in addition to files already +there. This option is useful when only certain files need to be +persistent, not the whole directory they're in, e.g. some +configuration files in a user's home directory. +.IP "\fBunion\fR" 4 +Save the rw branch of a union on the persistence media, so only the +changes are stored persistently. This can potentially reduce disk +usage compared to bind-mounts, and will not hide files added to the +read-only media. One caveat is that the union will use \fIDIR\fR from +the image's read-only file system, not the real file system root, so +files created after boot (e.g. by live-config) will not appear in the +union. This option will use the union file system specified by +live-boot's \fBunion\fR boot parameter. + +.SH DIRECTORIES +.IP "\fB/live/persistence\fR" 4 +All persistence volumes will be mounted here (in a directory +corresponding to the device name). The \fBpersistence.conf\fR file can +easily be edited through this mount, as well as any source directories +(which is especially practical for custom mounts using the +\fBlink\fR option). + +.SH EXAMPLES + +Let's say we have a persistence volume \fIVOL\fR with the a +\fBpersistence.conf\fR file containing the following four lines (numbered +for ease of reference): +.TP 7 +1. +/home/user1 link,source=config-files/user1 +.TP +2. +/home/user2 link,source=config-files/user2 +.TP +3. +/home +.TP +4. +/usr union +.PP +The corresponding source directories are: +.TP 7 +1. +\fIVOL\fR/config-files/user1 (but it would be \fIVOL\fR/home/user1 +without the \fBsource\fR option) +.TP +2. +\fIVOL\fR/config-files/user2 (but it would be \fIVOL\fR/home/user2 +without the \fBsource\fR option) +.TP +3. +\fIVOL\fR/home +.TP +4. +\fIVOL\fR/usr +.PP +It was necessary to set the \fBsource\fR options for 1 and 2, since +they otherwise would become nested with 3's source, which is invalid. +.PP +Line 3 will be taken care of before line 1 and 2 in order to prevent +custom mounts 1 and 2 from being hidden by 3. When line 3 is handled, +\fIVOL\fR/home is simply bind-mounted on /home. To illustrate what +happens for lines 1 and 2, let's say that the following files exist: +.TP 7 +a. +\fIVOL\fR/config-files/user1/.emacs +.TP +b. +\fIVOL\fR/config-files/user2/.bashrc +.TP +c. +\fIVOL\fR/config-files/user2/.ssh/config +.PP +Then the following links and directories will be created: +.TP 7 +Link: +/home/user1/.emacs -> \fIVOL\fR/config-files/user1/.emacs (from a) +.TP +Link: +/home/user2/.bashrc -> \fIVOL\fR/config-files/user2/.bashrc (from b) +.TP +Dir: +/homea/user2/.ssh (from c) +.TP +Link: +/home/user2/.ssh/config -> \fIVOL\fR/config-files/user2/.ssh/config +(from c) +.PP +One could argue, though, that lines 1 and 2 in the example +\fBpersistence.conf\fR file above are unnecessary since line 3 already +would make all of /home persistent. The \fBlink\fR option is +intended for situations where you don't want a complete directory to +be persistent, only certain files in it or its sub-directories. +.PP +Line 4 can be mounted at any time since its \fIDIR\fR (and source +directory) is completely disjoint from all the other custom +mounts. When mounted, \fIVOL\fR/usr will be the rw branch due to the +\fBunion\fR option, and will only contain the difference compared to +the underlying read-only file system. Hence packages could be +installed into /usr with great space-wise efficiency compared to +bind-mounts, since in the latter case all of /usr would have to be +copied into \fIVOL\fR/usr during the initial bootstrap. + +.SH SEE ALSO +\fIlive\-boot\fR(7) +.PP +\fIlive\-build\fR(7) +.PP +\fIlive\-config\fR(7) +.PP +\fIlive\-tools\fR(7) + +.SH HOMEPAGE +More information about live\-boot and the Live Systems project can be found on the homepage at <\fIhttp://live-systems.org/\fR> and in the manual at <\fIhttp://live-systems.org/manual/\fR>. + +.SH BUGS +Bugs can be reported by submitting a bugreport for the live\-boot package in the Bug Tracking System at <\fIhttp://bugs.debian.org/\fR> or by writing a mail to the Live Systems mailing list at <\fIdebian-live@lists.debian.org\fR>. + +.SH AUTHOR +live\-boot was written by Daniel Baumann <\fImail@daniel-baumann.ch\fR>. -- cgit v1.2.3