While working in IBM , sometimes we needed to loginto unix servers and check out application log files . So basic knowledge on Unix command is must if you wanna make your career in IT domain .. moreover interviewers tend to ask some unix commands to test your Unix knowledge . So let us learn about most commonly used Unix commands in organizations
1:-
Ls :- Lists your files .
LS-L :- Lists files in long format with important information of the file such as size , owner of the file … etc .
LS-A :- Lists all files .
2:-
ps -u username :-This will list all your processes along with the process ids.This is particularly useful if you wanna know about an unneeded process that is using to muck of processor and RAM and you wanna kill it .. for that you must know the process ID .
3:-
CAT :- CAT command can be used for three main functions with regard to text files: displaying them, combining copies of them and creating new ones. check out the CAT commands MAN page ofr detailed information on it
4:-
GREP string filename(s) :- Used for matching and finding a String in a particular file . Grep comes in several varieties (grep, egrep, and fgrep) run man command_name to know more about them .
5:-
Pipes ( | ) :- This is one of the most important feature of Unix . | symbol allows interprocess communication . Using pipes you can combine multiple commands in one statement .
6:-
tail file_name :- Tail command reads the few lines at the endof of a file and writes the read lines to the console .
tail -n file_name :- N is an integer it , if this command is used .. Only last N lines of the file_name would be displayed to the console .
7:-
head file_name :- Tail command reads the first few lines of a file and writes the read lines to the console .
head -n file_name :- N is an integer it , if this command is used .. Only first N lines of the file_name would be displayed to the console .
9:-
cd :- Simplest command of the all , it is used to change a directory . This is useful because sometimes you need to use pipes with them.
10:
DU:- shows the disk usage of the files and directories in filename . du -s gives only a total
11:-
KILL process_id :- This will kill a process with process_id you’ve mentioned . If you’ll kill the root process of any application all other child processes would be killed .
12:-
ff :- This command finds file anywhere in your unix system . This is also an important command
