Basic Linux commands and links

Thursday, September 21, 2006

These are some of the common linux OS commands for checking various system parameters.

To check for OS version
# uname -a
To check 32 bit or 64 bit
# uname -m
To check memory
# cat /proc/meminfo
to check CPU info
# cat /proc/cpuinfo
to check linux version
# cat /etc/redhat-release
to check hard disk space
# df -h or df -k
to check kernel parameters
# cat /etc/sysctl.conf
Finding files
# whereis filename
Getting to GUI screen. The default boot runlevel is set in the file /etc/inittab with the initdefault variable
# startx or # init 5
Starting and stopping services (eg samba services)
# service smb start
# service smb stop
# service smb status
the chkconfig command can be used to adjust which applications start at each runlevel
# chkconfig --list
CRONTAB Basic
# crontab -e
# crontab -l
A crontab file is comprised of six fields:
fields values
------ ------
Minute 0-59
Hour 0-23
Day of month 1-31
Month 1-12
Day of Week 0 - 6, with 0 = Sunday

Some common linux commands for checking Oracle

List all Oracle error messages from the alert.log file
"grep"
-v : show lines that do not contain the string
-h : basic usage description
# grep ORA- alert.log
Find out file system usage for Oracle destination
# df -k grep oradata

Some useful Linux links and tutorial