Sysvinit-2.85
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## Sysvinit-2.85

The Sysvinit package contains programs for controlling the startup, running, and shutdown of your system.

    Approximate build time:  0.1 SBU
    Required disk space:     0.9 MB

Sysvinit installation depends on: Binutils, Coreutils, GCC, Glibc, Make.

### Installation of Sysvinit

When run-levels are changed (for example, when halting the system), init sends termination signals to those processes that init itself started and that shouldn't be running in the new run-level. While doing this, init outputs messages like “Sending processes the TERM signal” which seem to imply that it is sending these signals to all currently running processes. To avoid this misinterpretation, you can modify the source so that these messages read like “Sending processes started by init the TERM signal” instead:

    cp src/init.c{,.backup}
    sed 's/Sending processes/& started by init/g' \
        src/init.c.backup > src/init.c

Compile Sysvinit:

    make -C src

Then install it:

    make -C src install

### Configuring Sysvinit

Create a new `/etc/inittab` file by running the following:

    cat > /etc/inittab << "EOF"
    # Begin /etc/inittab

    id:3:initdefault:

    si::sysinit:/etc/rc.d/init.d/rc sysinit

    l0:0:wait:/etc/rc.d/init.d/rc 0
    l1:S1:wait:/etc/rc.d/init.d/rc 1
    l2:2:wait:/etc/rc.d/init.d/rc 2
    l3:3:wait:/etc/rc.d/init.d/rc 3
    l4:4:wait:/etc/rc.d/init.d/rc 4
    l5:5:wait:/etc/rc.d/init.d/rc 5
    l6:6:wait:/etc/rc.d/init.d/rc 6

    ca:12345:ctrlaltdel:/sbin/shutdown -t1 -a -r now

    su:S016:once:/sbin/sulogin

    1:2345:respawn:/sbin/agetty tty1 9600
    2:2345:respawn:/sbin/agetty tty2 9600
    3:2345:respawn:/sbin/agetty tty3 9600
    4:2345:respawn:/sbin/agetty tty4 9600
    5:2345:respawn:/sbin/agetty tty5 9600
    6:2345:respawn:/sbin/agetty tty6 9600

    # End /etc/inittab
    EOF

### Contents of Sysvinit

Installed programs: halt, init, killall5, last, lastb (link to last), mesg, pidof (link to killall5), poweroff (link to halt), reboot (link to halt), runlevel, shutdown, sulogin, telinit (link to init), utmpdump and wall

### Short descriptions

halt normally invokes shutdown with the -h flag, except when already in run-level 0, then it tells the kernel to halt the system. But first it notes in the file `/var/log/wtmp` that the system is being brought down.

init is the mother of all processes. It reads its commands from `/etc/inittab`, which normally tell it which scripts to run for which run-level, and how many gettys to spawn.

killall5 sends a signal to all processes, except the processes in its own session -- so it won't kill the shell running the script that called it.

last shows which users last logged in (and out), searching back through the file `/var/log/wtmp`. It can also show system boots and shutdowns, and run-level changes.

lastb shows the failed login attempts, as logged in `/var/log/btmp`.

mesg controls whether other users can send messages to the current user's terminal.

pidof reports the PIDs of the given programs.

poweroff tells the kernel to halt the system and switch off the computer. But see halt.

reboot tells the kernel to reboot the system. But see halt.

runlevel reports the previous and the current run-level, as noted in the last run-level record in `/var/run/utmp`.

shutdown brings the system down in a secure way, signaling all processes and notifying all logged-in users.

sulogin allows the superuser to log in. It is normally invoked by init when the system goes into single user mode.

telinit tells init which run-level to enter.

utmpdump displays the content of the given login file in a friendlier format.

wall writes a message to all logged-in users.

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