systemd-vpick - Resolve paths to ".v/" versioned
directories
systemd-vpick [OPTIONS...]
[PATH...]
systemd-vpick resolves a file system path referencing a
".v/" versioned directory to a path to the newest (by version)
file contained therein. This tool provides a command line interface for the
systemd.v(7) logic.
The tool expects a path to a ".v/" directory as argument
(either directly, or with a triple underscore pattern as final component).
It then determines the newest file contained in that directory, and writes
its path to standard output.
Unless the triple underscore pattern is passed as last component
of the path, it is typically necessary to at least specify the
--suffix= switch to configure the file suffix to look for.
If the specified path does not reference a ".v/" path
(i.e. neither the final component ends in ".v", nor the
penultimate does or the final one does contain a triple underscore) its
specified path is written unmodified to standard output.
The following options are understood:
--basename=, -B
Overrides the "basename" of the files to look
for, i.e. the part to the left of the variable part of the filenames. Normally
this is derived automatically from the filename of the ".v"
component of the specified path, or from the triple underscore pattern in the
last component of the specified path.
Added in version 256.
-V
Explicitly configures the version to select. If
specified, a filename with the specified version string will be looked for,
instead of the newest version available.
Added in version 256.
-A
Explicitly configures the architecture to select. If
specified, a filename with the specified architecture identifier will be
looked for. If not specified only filenames with a locally supported
architecture are considered, or those without any architecture identifier.
Added in version 256.
--suffix=, -S
Configures the suffix of the filenames to consider. For
the ".v/" logic it is necessary to specify the suffix to look for,
and the ".v/" component must also carry the suffix immediately
before ".v" in its name.
Added in version 256.
--type=, -t
Configures the inode type to look for in the
".v/" directory. Takes one of "reg", "dir",
"sock", "fifo", "blk", "chr",
"lnk" as argument, each identifying an inode type. See
inode(7) for details about inode types. If this option is used inodes
not matching the specified type are filtered and not taken into consideration.
Added in version 256.
--print=, -p
Configures what precisely to write to standard output. If
not specified prints the full, resolved path of the newest matching file in
the ".v/" directory. This switch can be set to one of the following:
•If set to "filename", will print only
the filename instead of the full path of the resolved file.
•If set to "version", will print only
the version of the resolved file.
•If set to "type", will print only the
inode type of the resolved file (i.e. a string such as "reg" for
regular files, or "dir" for directories).
•If set to "arch", will print only the
architecture of the resolved file.
•If set to "tries", will print only the
tries left/tries done of the resolved file.
•If set to "all", will print all of the
above in a simple tabular output.
Added in version 256.
--resolve=
Takes a boolean argument. If true the path to the
versioned file is fully canonicalized (i.e. symlinks resolved, and redundant
path components removed) before it is shown. If false (the default) this is
not done, and the path is shown without canonicalization.
Added in version 256.
-h, --help
Print a short help text and exit.
--version
Print a short version string and exit.
Use a command like the following to automatically pick the newest
raw disk image from a ".v/" directory:
$ systemd-vpick --suffix=.raw --type=reg /var/lib/machines/quux.raw.v/
This will enumerate all regular files matching
/var/lib/machines/quux.raw.v/quux*.raw, filter and sort them according to
the rules described in systemd.v(7), and then write the path to the
newest (by version) file to standard output.
Use a command like the following to automatically pick the newest
OS directory tree from a ".v/" directory:
$ systemd-vpick --type=dir /var/lib/machines/waldo.v/
This will enumerate all directory inodes matching
/var/lib/machines/waldo.v/waldo*, filter and sort them according to the
rules described in systemd.v(7), and then write the path to the
newest (by version) directory to standard output.
For further examples see systemd.v(7).
On success, 0 is returned, a non-zero failure code otherwise.