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Linux System Management

June 14th, 2009

Environment

Linux System Management env        Show all environment variables.
export        Set the value of a variable so it is visible to all subprocesses that belong to the current shell.
printenv        Print all or part of environment.
reset        Restores runtime parameters for session to default values.
set        Shows how the environment is set up. This is a builtin bash command.

Library management

ldconfig        Updates the necessary links for the run time link bindings.
ldd        Tells what libraries a given program needs to run.
ltrace        A library call tracer.
trace        Same as ltrace.

Module and kernel management

depmod        Handle loadable modules automatically. Creates a makefile-like dependency file.
dmesg        Print or control the kernel ring buffer. This shows the last kernel startup messages.
genksyms        Generate symbol version information.
insmod        Install loadable kernel module.
lsmod        List currently installed kernel modules.
modprobe        Used to load a set of modules that are marked with a specified tag.
rmmod        Unload loadable modules.

Runtime level management

exit        Terminates the shell.
halt        Stop the system.
init        Process control initialization.
initscript        Script that executes inittab commands.
logout        Log the user off the system.
poweroff        Brings the system down.
reboot        Reboot the system.
runlevel        List the current and previous runlevel.
setsid        Run a program in a new session.
shutdown        If your system has many users, use the command “shutdown -h +time message”, where time is the time in minutes until the system is halted, and message is a short explanation of why the system is shutting down.
# shutdown -h +10 ‘We will install a new disk. System should be back on-line in three hours.’
telinit        By requesting run level 1 a system can be taken to single user mode.

System Configuration tools

ctrlaltdel        Set the function of the ctrl alt del combination.
isapnp        Configure ISA plug and play devices.
kbdconf         A Redhat Linux tool which configures the /etc/sysconfig/keyboard file which specifies the location of the keyboard map file. This is a GUI based tool.
kbdrate        Set the keyboard repeat rate and delay time.
kernelcfg        A Redhat GUI kernel configuration tool, Start X, then run it from a console session.
linuxconf        Redhat’s GUI linux system configuration tool.
lspci        List all pci devices.
mesg        Control write access to your terminal.
mouseconfig        A Redhat Linux tool used to configure the /etc/sysconfig.mouse file. This is a GUI tool.
ndc        Script file used to restart, stop, start the DNS server.
Printtool        Redhat’s GUI printer configuration tool.
quota        Display disk usage and limits.
quotacheck        Scan a filesystem for disk usages.
quotaoff        Turn file system quotas off.
quotaon        Turn file system quotas on.
samba        Script file used to stop, start, restart samba services when not run using inetd.
setpci        Configure pci devices.
setserial        Set/get serial port information.
setterm        Set terminal attributes.
setup        Set up devices and file systems.
stty        Used to configure and print the console devices.
swapon        Enable devices and files for paging and swapping.
swapoff        Disable devices and files for paging and swapping.
timeconfig        A Redhat Linux tool used to configure the /etc/sysconfig/clock file. This is a GUI tool used to set timezone and whether or not the clock is set to GMT time.
tset        Used to initialize terminals.

System Information

arch        Print machine architecture.
df         Shows disk free space.
du        Shows disk usage.
free        Display used and free memory on the system.
ipcrm        Provide information on ipc facilities.
ipcs        Same as ipcrm.
lsdev        Display information about installed hardware via files in the /proc directory.
lsof        List open files.
lspci        List PCI devices .
pnpdump        Lists ISA plug and play devices resource information.
procinfo        Display system status gathered from proc.
pstree        Display a tree of processes.
runlevel        Find the current and previous system runlevel.
strace        Trace ssytem calls and signals for a binary program.
stty        Change and print terminal line settings.
tload        Prints a graphic representation of the system load average.
tty        Print the filename of the terminal connected to standard input.
uname        Print system information, Prints Linux.
vmstat        Report virtual memory statistics.
xcpustate        Displays CPU states (idle, nice, system, kernel) statistics. Runs in X?

System Logging

klogd        Kernel log daemon which intercepts and logs Linux kernel messages.
logger        Make entries in the system log.
syslogd        Linux system logging utilities.
sysklogd        Linux system logging utilities.

System Security

System time
cal        Calendar.
clock        Used to change or get current time. The command “clock -–w” sets the hardware clock.
date        Print or set the system date and time.
hwclock        Set or read the hardware CMOS clock.
timed        Time server daemon to synchronize the host’s time with other machines, normally invoked at boot time from the rc(8) file.
timedc        Timed control program.
tzset        Used to change the users private time zone by setting the TZ environment variable.
uptime        Reports how long the system has been running.
zdump        Prints the current time in each zonename named on the command line.
zic        Reads text from files named on the command line and creates time conversion files.

X Management and programs

SuperProbe        Probe video hardware.
Xconfigurator        The Redhat tool used during system setup to configure X.
xconsole        Displays messages usually sent to /dev/console.
xf86config        Older version of XF86Setup.
XF86Setup        A newer X configuration program with a GUI interface which modifies the “/etc/X11/XF86Config” configuration file.
xvidtune        This program will test video modes on the fly without modification to your X configuration. Read the usr/X11R6/lib/X11/doc/VideoModes.doc file before running this program.

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