tinyramfs/docs/tinyramfs.hooks.7.scd
2021-05-10 16:02:38 +03:00

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tinyramfs.hooks(7)
# NAME
Tinyramfs - hooks and related stuff
# DESCRIPTION
Hooks can be located in */usr/share/tinyramfs/hooks* (system path) and
*/etc/tinyramfs/hooks* (user path). Tinyramfs also allows you to specify custom
location via *-H* option. See *tinyramfs*(8) for more information.
Hooks provides a way to extend build and init process. Hooks must be written in
POSIX shell. Bashisms and other non-portable extensions are forbidden. In order
to write hooks you must know about hook structure.
- <hook> - directory of hook scripts
- <hook> - invoked in build process.
- <hook>.init - invoked in init process.
- <hook>.init.late - invoked after root filesystem was mounted.
## MAN PAGE SYNTAX
```
- B: extension can be used in build process
- I: extension can be used in init process
- BI: extension can be used in both processes
```
# EXTENSIONS
Tinyramfs also provides some extensions and environment variables to easily
interact with build and init system.
## BI: print <message>
Print message to stdout.
## BI: panic [message]
If message was not specified, then tinyramfs will print default error
message. otherwise message will be printed.
## B: copy_module <full path>
Copy kernel module by path to tinyramfs working directory.
## B: copy_binary <name or full path>
If full path was specified and it's has executable bit, then it's will
be copied to /bin location of tinyramfs working directory.
If name was specified, then tinyramfs will try to find command by name
in PATH. If it's success, command will be copied to /bin location of
tinyramfs working directory. Otherwise error message will appear.
## B: copy_file <file> <destination> <mode> <strip>
<file> must be full path to file.
<destination> must be full path where <file> should be stored. Tinyramfs
will automatically create all leading directories if they aren't exist
already. Also no need to prepend path of tinyramfs working directory.
<mode> permissions in octal format.
<strip> if was set to 1, then tinyramfs will attempt to run strip
on file. Tinyramfs will silently ignore errors if strip doesn't
exists or failed to strip binary.
## I: resolve_device <UUID|LABEL|/dev/\*|PARTUUID>
Sets *device* variable to full path of resolved UUID|LABEL|/dev/\*|PARTUUID
# VARIABLES
```
- BI: debug - 1 if debug mode enabled
- I: break - breakpoint for debugging
- B: tmpdir - full path of tinyramfs working directory (initramfs rootfs in future)
- B: kernel - kernel version
- B: moddir - modules directory
- B: init - path to init script
- B: helper - path to device-helper script
- B: config - config location
- B: output - output path
- BI: see tinyramfs.config(5)
```
# EXAMPLES
This example will show how to handle soft dependencies of ext4 module.
Create */etc/tinyramfs/hooks/ext4* directory and copy below scripts with
appropriate names to that directory. After that, prepend *ext4* to *hooks*
option in tinyrams config.
## ext4
```
print "Copying ext4 dependencies"
for _mod in crc32c libcrc32c; do
copy_module "$_mod"
done
```
## ext4.init
```
modprobe -a crc32c libcrc32c
```
# SEE ALSO
*tinyramfs*(8) *tinyramfs.config*(5) *tinyramfs.cmdline*(7) *tinyramfs.hooks*(7)