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66-scandir.md 8.35 KiB

title: The 66 Suite: 66-scandir author: Eric Vidal eric@obarun.org

66

Software

obarun.org

66-scandir

Handles the scandir for a given user. Designed to be either root or a branch of the supervision tree.

Interface

    66-scandir [ -h ] [ -z ] [ -v verbosity ] [ -l live ] [ -b|B ] [ -c ] [ -L log_user ] [ -s skel ] [ -o owner ] create|remove

This program creates or remove the scandir (directory containing a collection of s6‑supervise processes) for the current owner of the proccess depending on the provided options.

Exit codes

  • 0 success
  • 100 wrong usage
  • 111 system call failed

Options

  • -h : prints this help.

  • -z : use color.

  • -v verbosity : increases/decreases the verbosity of the command.

    • 1 : only print error messages. This is the default.
    • 2 : also print warning messages.
    • 3 : also print tracing messages.
    • 4 : also print debugging messages.

  • -l live : changes the supervision directory of service to live. By default this will be %%livedir%%. The default can also be changed at compile time by passing the --livedir=live option to ./configure. An existing absolute path is expected and should be within a writable and executable filesystem - likely a RAM filesystem.

  • -b : create specific files for boot. Only the root user can use this option. It is not meant to be used directly even with root. 66-boot calls it during the boot process.

  • -B : create specific files for boot inside a container. This option modifies some behaviors:

    • The ultimate output fallback (i.e. the place where error messages go when nothing catches them, e.g. the error messages from the catch-all logger and the s6-supervise process managing the catch-all logger) is not /dev/console, but the descriptor that was init's standard error.
    • Stopping the container with reboot will make the container's init program report being killed by a SIGHUP. Stopping it with poweroff will make it report being killed by a SIGINT. This is according to the reboot(2) specification.
    • Stopping the container with halt, however, is different. It will make the container's pid 1 read a number in the %%livedir%%/container/\<owner\>/halt file which contents the variable EXITCODE, and exit with the code it has read. (Default is 0.) This means that in order to run a command in a container managed by 66-boot and exit the container when the command dies while reporting the exit code to its parent, 66-boot use the %%skel%%/rc.init.container file instead of the %%skel%%/rc.init file. This file should be modified to launch the command that you want to start inside this container. Then you need to stop that container calling halt.
    • All the running services will be killed, all the zombies will be reaped, and the container will exit with the required exit code.

  • -c : run the system without a catch-all logger. On a non-containerized system, that means that all the logs from the s6 supervision tree will go to /dev/console, and that /dev/console will also be the default stdout and stderr for services running under the supervision tree: use of this option is discouraged. On a containerized system (when paired with the -B option), it simply means that these outputs go to the default stdout and stderr given to the container's init - this should generally not be the default, but might be useful in some cases.

  • -s skel : an absolute path. Directory containing skeleton files. This option is not meant to be used directly even with root. 66‑boot calls it during the boot process. Default is %%skel%%.

  • -L log_user : will run the catch-all logger as log_user. Default is %%s6log_user%%. The default can also be changed at compile-time by passing the ‑‑with‑s6‑log‑user=user option to ./configure.

  • -o owner : handles the scandir for the given owner. Only the root user can use this option. Note that owner can be any valid user on the system. However, the given user must have sufficient permissions to create the necessary directories at its location. That is %%livedir%% by default or the resulting path provided by the ‑l option.

Scandir creation process

When creating the scandir various files and directories will be created at the live directory.

If created with the user root, you will find the following in %%livedir%% (the directory created by default if ‑l is not passed and 0 being the corresponding UID for the root user):

  • %%livedir%%/scandir/0 : stores all longrun proccesses (commonly known as daemons) started by root.

  • %%livedir%%/tree/0 : stores any s6‑rc service database started by root.

  • %%livedir%%/log/0 : stores the catch-all logger when the scandir is created for a boot procedure with the ‑b option.

  • %%livedir%%/state/0 : stores internal 66 ecosystem files.

If the scandir was created with a regular user you will find the following in %%livedir%% (Default directories if ‑l is not passed and 1000 being the UID for the user):

  • %%livedir%%/scandir/1000

  • %%livedir%%/tree/1000

  • %%livedir%%/state/1000

The -B option create an extra directory at %%livedir%%/scandir/<owner>/container containing a file named halt. See 66-boot for further information.