Linux System Administration Commands
October 1, 2010Compression/decompression utilities (software installation):
compress <file> compress -d <file>.Z (or uncompress <file>.Z)
gzip <file> gzip -d <file>.gz (or gunzip <file>.gz)
tar cvf <device> <files> tar xvf <device>.tar
System Shutdown:
reboot
halt
shutdown [-h now] [-r now]
User Management:
1. To add a user
(a) adduser: add a new user account
(useradd, chfn, passwd)
(b) /etc/passwd
2. To delete a user:
(1) userdel [-r]: delete his home directory and passwd entry
- delete that user’s home directory: rm -rf /home/<user directory>
- delete his /etc/passwd entry
- delete his mail spool file: rm -f /var/spool/mail/<user file>
3. To modify a user:
(a) Usermod <name>
(b) /et/c/passwd (& /etc/group)
Group Management:
1. To add a group:
(a) Groupadd <group>
(b) /etc/group
2. To delete a group
(1) groupdel <group>
3. To modify a group
(1) Groupmod [-n <group_name>] <group>
User Disk Spack Management:
quota [-v]
Mounting and Unmounting file systems:
mount [-t <fstype>] <device> <mount point>
umount <mount point or device>
<fstype>: minix, ext, ext2, umsdos, msdos, iso9660, nfs, proc, swap
Devices:
IDE, EIDE (ATAPI):
/dev/hda1, /dev/hda2, …
/dev/hdb1, /dev/hdb2, …
SCSI:
/dev/sda1, /dev/sda2, …
/dev/sdb1, /dev/sdb2, …
floppy:
/dev/fd0, /dev/fd1, …
Disk-related commands:
fdisk <device>
mkfs [-t <fstype>] <device>
File system recovery:
fsck <device>
Disk space:
du <directory> : disk space usage
df : disk free space
Monitoring system efficiency:
top : show current process information
free : show current memory information
Program development (or software maintenance):
GNU C/C++ compiler (gcc), GNU make, …
Rebuilding & Upgrading the kernel:
1. Get the latest Linux kernel (2.2.x)
2. Uncompress kernel source: tar zxvf
3. Building the kernel:
cd /usr/src/linux
make config
make dep; make clean
make zImage (or make zlilo)
mv /vmlinuz /vmlinuz.old (if necessary)
cp /usr/src/linux/arch/i386/boot/zImage /vmlinuz (or any other file as specified in /etc/lilo.conf)
joe /etc/lilo.conf (if necessary)
/sbin/lilo
sync; sync; reboot
Linux installation:
(1) get Linux package (Slackware)
(2) Creating boot & root disks: (May be skipped if CD-ROM is bootable)
- In DOS:
o rawrite <disk image> <floppy disk>
- In UNIX or Linux:
- cat <disk image> > <device>
- dd if=<disk image> of=<device>
(3) boot from floppy disks (or CD-ROM)
(4) fdisk <device> (if needed)
(5) reboot
(6) setup: start installing Linux…
(7) X Window configuration: SuperProbe & xf86config à the most difficult!
LILO (Linux Loader) – a Boot Manager
- Installing LILO:
/sbin/liloconfig &nb
sp; : set
up /etc/lilo.conf
/sbin/lilo : update boot sector, and create /boot/map
see LILO mini-HOWTO for more details
System configuration files:
/etc/inittab : specify the programs to execute at each run level
/etc/fstab : file system to mount
/etc/mtab : last mounted file system
/etc/passwd : user/password
/etc/motd : displayed after logging in
/etc/issue : displayed before logging in
/etc/rc.d/rc.* : rc scripts executed at booting time
Documentation:
Man pages
/usr/doc/*
(/usr/doc/faq/*: for FAQ’s and HOWTO’s if they are installed)
/usr/src/linux/Documentation/*
LDP, CLDP, …