Linux commands

To display all permissions..of all files on current directory.
>ls -al


clear screen:
>clear

To traverse root to root directory
>cd ../../


to delete the folder recursively.
>rm -R pictures


to delete focibly a filename
>rm -f abc.txt


to copy a file to local current directory
>cp /home/abc/*.* .


to set an environment variable like TOP to ~/BA/SOL/test
>setenv TOP ~/BA/SOL/test


To set an environment variable in bash like TOP to ~/BA/SOL/top
>export TOP=~/BA/SOL/top


To check the value of environment variable like TOP
>echo $TOP


to flush DNS cache on Linux:
- To restart the nscd daemon, type 
/etc/rc.d/init.d/nscd restart 
in your terminal
- Once you run the command your linux DNS cache will flush.

to rename a file

>mv abc.c abc

>find /opt/CA -name "m_replace" -print

similar to explorer . in windows we can use "nautilus ." without double quotes.

to share files we can go to /mnt/httpd and open it

command to know suse verion on suse linux:

cat /etc/SuSE-release

How to check physical memory in solaris:

/usr/sbin/prtconf -v |grep Memory

Command to Know processid:
pidof processname
example:>pidof abserver
>23434


command to kill a process:
you can try:
>kill processID
>pkill processname
Forcible kill after trying kill with -1 and -2 is
>kill -9 processID
killing multiple instances of same process
>killall processName
>killall -9 processName


To list all processes running along with mem and cpu usage:
>ps aux
example:
>ps aux | grep uniserver
reference link: http://www.linfo.org/ps.html

How to create core file in Linux:
>ulimit -c unlimited
now core file will be generated like core.12345 where 12345 is pid of process. created in the location where process binary exist.
(or )
>gcore process-ID

How to get callstack of running process:
pstack processId
example:
>pstack 21345
This will give same output as gcore command coredump, analyzing it via gdb command
using gdb to get callstack:
>gdb programname core-file
> where //to get call stack
>bt    //to get callstack
>quit   //to come out of gdb