In Linux and Solaris Operating Sytems the Run levels are considered as more important.
If the Runlevels are used improperly then there will be problem in booting up and using the system.
Linux Run Levels
============
0 - halt (Do NOT set initdefault to this)
1 - Single user mode
2 - Multiuser, without NFS
3 - Full multiuser mode
4 - unused
5 […]
The sar command is used to sample and report various cumulative statistic counters maintained by the operating system.
SYNOPSIS
sar [-dgpu] [-n mode] [-o filename] t [n]
sar [-dgpu] [-n mode] [-e time] [-f filename] [-i seconds] [-s time]
The sar command writes to standard output the contents of selected cumulative activity counters in the operating system. The accounting […]
vmstat reports information about processes, memory, paging, block IO, traps, and cpu activity.
The first report produced gives averages since the last reboot. Addi-tional reports give information on a sampling period of length delay.The process and memory reports are instantaneous in either case.
vmstat - Report virtual memory statistics
SYNOPSIS
vmstat [-a] […]
The iostat command is used for monitoring system input/output device loading by observing the time the devices are active in relation to their average transfer rates. The iostat command generates reports that can be used to change system configuration to better balance the input/output load between physical disks.
iostat - Report Central Processing Unit (CPU) statistics […]
Oracle Database 10g Release 2 (in Linux) requires the kernel parameter settings shown below. The values given are minimums, so if your system uses a larger value, don’t change it.
kernel.shmall = 2097152
kernel.shmmax = 536870912
kernel.shmmni = 4096
kernel.sem = 250 32000 100 128
fs.file-max = 65536
net.ipv4.ip_local_port_range = 1024 65000
net.core.rmem_default=262144
net.core.wmem_default=262144
net.core.rmem_max=262144
net.core.wmem_max=262144
Pgrep command in unix
pgrep command replaces the combination of the ps , grep , egrep commands.
Example:
check oracle pmon process running in unix server
Monitoring swap space in linux /solaris
In LINUX Free command displays the total amount of free and used physical memory and swap space in the
system, as well as the buffers and cache consumed by the kernel.
[oracle@tritya oracle]$ free
LS command to show hidden
files and hidden characters in a file
ls -a command shows hidden files
ex : ls -a
[oracle@tritya TEST]$ ls -al
find command to find files with specific permission
Example : To Find files with 777 permission
[oracle@tritya oracle]$ find . -type f -perm 777 -exec ls -l {} \;
-rwxrwxrwx 1 oracle dba 19210126 Jun 9 11:35 ./soft/jre-6u6-linux-i586-rpm.bin
[oracle@tritya oracle]$
To Change the shell prompt in bourne shell add the following line in the user profile
export PS1=”ANY NAME > ”
[oracle@tritya oracle]$ export PS1=”ANY NAME # “ANY NAME #
