make linux easy

List of useful inux command which i came across

1. ctrl + r     to know the old commands typed
2. !ca    this execute old executed cat command
a. first typed    gdb ../test.out
b. !gd    to execute above command
3a. to create the new command in the linux using /etc/bashrc file:
example:

-> my new command "lsf" tells the output of the 3 commands:
-> Add this command at the end of the /etc/bashrc file
function lsf
{
        ls -ltrh | more
        ls | wc
        date
}

3b. or another way to create new command:

a. put necessary command in one file.
b. then change its mode and copy into /bin. so you can access from anywhere in the linux prompt
ex:
[root@localhost ~]# cat mycmd
killall -9 telnet
ps -aH
[root@localhost ~]# chmod 777 mycmd
[root@localhost ~]# cp mycmd /bin/
[root@localhost ~]# cd /home/
[root@localhost home]# mycmd
telnet: no process killed
  PID TTY          TIME CMD
32199 pts/42   00:00:00 vim
 1958 pts/40   00:00:00 vim
 1971 pts/39   00:00:00 vim
12485 pts/55   00:00:01 vim
12486 pts/55   00:00:00   cscope


4. how to use cscope?
a. #cscope -uR    for first time
b. #cscope -d        for next time to use exisiting cscope.out file