Unix Miscellaneous commands

1. ls
2. pwd
3. ln
4. head
5. tail
6. cal
7. ps
8. kill
9. who
10. whoami
11. uptime
12. ut

ls : This command displays files and directories in columnar format.

Example:

$ ls

$ ls -S                

Aarrange the files based on the size(S is upper letter)

$ ls -l                

long listing the files

$ ls -a                

Displays hidden files

$ ls -i 

Displays inodes for each file

$ ls -R            

Displays all directories along with subdirectories in current working directory.

creating a hidden file:

$ cat >.employee.txt            

Wild card characters using with ls command.

?   Represents single character

*   Represents gruop of characters

[  ]   Represents searching pattern

Examples:

$ ls ?                Displays files with one letter

$ ls x*               Displays files which are starting with 'x'

$ ls ???           Displays files with 3 letters

$ ls *.out          Displays all the files with extension 'out'

$ ls [a-z]           Displays single character files which are from a to z

$ ls [a-z]*          Displays files starting with a to z

$ rm ?               Removes the files with single character

$ rm *.c             Removes the files with extension 'c'

$ cp ? chennai       Single digit files will be copied into directory 'chennai'

pwd : This command shows current working directory in unix

$ pwd

head :  Used to display First lines of the file

Syntax:

$ head -n  filename

Example:

$ head  paypal.txt

     This command dispalys default 10 lines of the file paypal.txt

$ head -n15  paypal.txt

    This command displays 15 lines of the file paypal.txt

$ head -n3  paypal.txt

    This command displays 3 lines of the file paypal.txt

tail : Used to display last lines of the file.

Ex:

$ tail paypal.txt

      This command displays default last 9 lines.

$ tail -n5 paypal.txt

      This command displays last 4 lines of the file.

$ tail -n15 paypal.txt

       This command displays last 14 lines of the file.

cal command: Used for display the calender.

Syntax:

$ cal

$ cal  [Month No] [Year]

Ex:

$ cal 2011                Displays 2011 calender

$ cal  2   2011          Displays Feb month in 2011 year

ln :

1.This will create link between 2 files.(2nd file should new one)

2. If one file modified another one affected.

Ex:

$ln paypal.txt    funpal.txt

ps : Knowing backgroud process running /stopped

$ ps pid     

kill : Used for terminating the process

Ex:

$ kill  pid

who : Used for to display who are working in the system

Ex:

$ who

whoami: Display my user name/accout

Ex:

$ whoami

uptime: This command used for display load in the server.

$ uptime

ut: displays current unix time

advance_date : Used to time forward the unix server.

$ advance_date

reset_time.py : Used to reset time and date in unix server.

$ reset_time.py