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# Sysvinit

## Contents

The Sysvinit package contains the pidof, last, lastb, mesg, utmpdump, wall, halt, init, killall5, poweroff, reboot, runlevel, shutdown, sulogin and telinit programs.

## Description

### pidof

Pidof finds the process id's (pids) of the named programs and prints those id's on standard output.

### last

last searches back through the file /var/log/wtmp (or the file designated by the -f flag) and displays a list of all users logged in (and out) since that file was created.

### lastb

lastb is the same as last, except that by default it shows a log of the file /var/log/btmp, which contains all the bad login attempts.

### mesg

Mesg controls the access to your terminal by others. It's typically used to allow or disallow other users to write to your terminal.

### utmpdump

utmpdumps prints the content of a file (usually /var/run/utmp) on standard output in a user friendly format.

### wall

Wall sends a message to everybody logged in with their mesg permission set to yes.

### halt

Halt notes that the system is being brought down in the file /var/log/wtmp, and then either tells the kernel to halt, reboot or poweroff the system. If halt or reboot is called when the system is not in runlevel 0 or 6, shutdown will be invoked instead (with the flag -h or -r).

### init

Init is the parent of all processes. Its primary role is to create processes from a script stored in the file /etc/inittab. This file usually has entries which cause init to spawn gettys on each line that users can log in. It also controls autonomous processes required by any particular system.

### killall5

killall5 is the SystemV killall command. It sends a signal to all processes except the processes in its own session, so it won't kill the shell that is running the script it was called from.

### poweroff

poweroff is equivalent to shutdown -h -p now. It halts the computer and switches off the computer (when using an APM compliant BIOS and APM is enabled in the kernel).

### reboot

reboot is equivalent to shutdown -r now. It reboots the computer.

### runlevel

Runlevel reads the system utmp file (typically /var/run/utmp) to locate the runlevel record, and then prints the previous and current system runlevel on its standard output, separated by a single space.

### shutdown

shutdown brings the system down in a secure way. All logged-in users are notified that the system is going down, and login is blocked.

### sulogin

sulogin is invoked by init when the system goes into single user mode (this is done through an entry in /etc/inittab). Init also tries to execute sulogin when it is passed the -b flag from the bootmonitor (eg, LILO).

### telinit

telinit sends appropriate signals to init, telling it which runlevel to change to.

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