Interview Linux/Unix Command Examples

1.Grep Command in Linux/Unix Examples :

a.Find the word present in a file

grep <word> <filename>

b.Find the word present in the current and sub directories

grep -r <word> .

"." <dot> represents the current directory and "-r" represents recursive

2.df command for disk free space in linux


[ivreddy@localhost test]$ df -h
Filesystem            Size  Used Avail Use% Mounted on
/dev/sda2              16G  4.0G   11G  27% /
tmpfs                1012M  432K 1012M   1% /dev/shm
/dev/sda1             291M   30M  247M  11% /boot
/dev/sr0               46M   46M     0 100% /media/Reliance
[ivreddy@localhost test]$

3.top command gives an ongoing look at processor activity in real time. It displays a listing of the most CPU-intensive tasks on the system

[admin@localhost test]$ top
  PID USER      PR  NI  VIRT  RES  SHR S %CPU %MEM    TIME+  COMMAND        
 1942 root      20   0 75076  26m 8372 S 10.3  1.3   2:34.03 Xorg            
 2381 admin   20   0  315m  55m  23m S  3.3  2.7   4:56.94 firefox        
 2357 admin   20   0 51096  12m 9496 S  2.3  0.6   0:12.77 gnome-terminal  
 8161 admin   20   0  2676 1116  868 R  0.7  0.1   0:00.20 top            
 2242 admin   20   0 91836  21m  16m S  0.3  1.1   0:44.49 vmtoolsd        
    1 root      20   0  2852 1408 1192 S  0.0  0.1   0:02.27 init

4.sort command in linux

[ivreddy@localhost Desktop]$ cat file
linux
dos
unix
windows
unix
[ivreddy@localhost Desktop]$ sort file
dos
linux
unix
unix
windows
// sort -u <file> will display the uniq records
[ivreddy@localhost Desktop]$ sort -u file
dos
linux
unix
windows
// sort -r <file> will display the  records in reverse order
[ivreddy@localhost Desktop]$ sort -r file
windows
unix
unix
linux
dos
[ivreddy@localhost Desktop]$