Basic Linux Commands

To check the Size of RAM in Unix

HP-UX

swapinfo –tm

Linux

free –m

free -g

AIX

lsdev -C|grep mem

Solaris

prtconf|grep -i mem

To Check number of CPU’s in the Server

Linux

cat /proc/cpuinfo | grep “processor”|wc –l

HP-UX

ioscan -C processor | grep processor | wc –l

SUN Solaris

psrinfo -v|grep “Status of processor”|wc –l

AIX

lsdev -C|grep Process|wc –l

To identify High Disk I/o using Unix command

/usr/bin/ps -eo pid,user,pcpu,args | grep -v %CPU |  sort -nbk 3 | tail -25

To report the current CPU Activity

sar -u 1 5

sar utility can be used to provide various information about the server resources.

In the above example the parameters used and the details are as mentioned below
-u option is for CPU related information
1 is the frequency of execution of the command in seconds
5 is the number of times the command should be executed.
So the command displays the CPU information every 1 second for 5 times.

It reports the CPU related usage by the user(%usr), system(%sys), the CPU Wait for I/O(%wio) and the Idle Percentage(%idle).

Sample Output

14:08:17    %usr    %sys    %wio   %idle   physc
14:08:18      25        0          0           75       4.00
14:08:19      25        0          0           74       4.00
14:08:20      25        0          0           75       4.00
14:08:21      25        0          0           75       4.00
14:08:22      25        0          0           75       4.03
Average       25        0          0           75       4.01

Finding files in Unix based on specific criteria

FIND FILES THAT WERE MODIFIED/ACCESSED WITHIN A SPECIFIED TIME

            $   find  /<your path>  -mtime   1  -type   f 

This command would return files modified  in the last 24 hours .
You can use -mtime option to return a list of files that were last modified N*24 hours ago. For example to find a file in last month (30 days) you would need to use -mtime +30 options.

• -mtime +30   means you are looking for a file modified 30 days ago.
• -mtime -30    means less than 30 days.
• -mtime 30      If you skip + or – it means exactly 30 days

      -type f      searches only for files and not directories

To list the files in the directory tree that were modified within the past five minutes, type

$  find /<your path>  -mmin -5

To return a list of files that were accessed in the last 24 hours you would need to use the–atime option.

$  find  /<your path>   -atime   1  -type   f  ******************************************************************

FINDING FILES WITH A SPECIFIC EXTENTION WITHIN A DIRECTORY

         $  find   /<your path>   -name  “*.cfg”

The command –name matches the file names with the specified pattern

*****************************************************************

FINDING FILES BASED ON THE FILE-PERMISSIONS

Files with execute permission for group :

$ find /<your path>  -perm g=x   -type f 

Files with execute permission for others:

$ find /<your path>  -perm  o=x   -type f

Where ‘g’ denotes groups and ‘o’ denotes others. x denotes execute permission.

*****************************************************************

KILLING ACTIVE UNIX PROCESSES FOR SPECIFIC COMPONENTS

ps -ef |grep applmgr |grep <Component Name> |grep -v grep |awk ‘{print $2}’ |xargs kill -9For example to kill all active forms processes, we can use the following command:

ps -ef |grep applmgr |grep frm | grep -v grep |awk '{print $2}' |xargs kill -9

ps -ef | grep FNDLIBR | grep -v grep | awk '{print $2}' | xargs kill -9        -- to kill all FNDLIBR

Linux commands:

to check the load average :

$ cat  /proc/loadavg

2.70 2.45 2.13 1/450 6959

Use the below command to check the number of CPU cores on the server.

$ grep 'process' /proc/cpuinfo | wc -l

32

[oracle@UATORADB2 ~]$ cat /proc/cpuinfo |grep core|wc -l

48

[oracle@UATORADB2 ~]$ cat /proc/cpuinfo |grep proc|wc -l

24

--To check process count by each user

ps hax -o user | sort | uniq -c

Finding the processes that are causing high I/O

iotop

to check the proccess reads and writes:

cat /proc/16528/io

Finding what files are being written too heavily:

lsof -p 16528