Unix Tutorial 2 : Basic Unix Commands

#1) cal: Displays the calendar.

• Syntax: cal [[month] year]
• Example: display the calendar for April 2018
  • $ cal 4 2018

#2) date: Displays the system date and time.

• Syntax: date [+format]
• Example: Display the date in dd/mm/yy format
  • $ date +%d/%m/%y

#3) banner: Prints a large banner on the standard output.

• Syntax: banner message
• Example: Print “Unix” as the banner
  • $ banner Unix

#4) who: Displays the list of users currently logged in

• Syntax: who [option] … [file][arg1]
• Example: List all currently logged in users
  • $ who

#5) whoami: Displays the user id of the currently logged in user.

• Syntax: whoami [option]
• Example: List currently logged in user
• $ whoami

#6) touch: Create a new file or update its timestamp.

• Syntax: touch [OPTION]…[FILE]
• Example: Create empty files called ‘file1’ and ‘file2’
  • $ touch file1 file2

#7) cat: Concatenate files and print to stdout.

• Syntax: cat [OPTION]…[FILE]
• Example: Create file1 with entered cotent
  • $ cat > file1
  • Hello
  • ^D

#8) cp: Copy files

• Syntax: cp [OPTION]source destination
• Example: Copies the contents from file1 to file2 and contents of file1 is retained
  • $ cp file1 file2

#9) mv: Move files or rename files

• Syntax: mv [OPTION]source destination
• Example: Create empty files called ‘file1’ and ‘file2’
  • $ mv file1 file2

#10) rm: Remove files and directories

• Syntax: rm [OPTION]…[FILE]
• Example: Delete file1
  • $ rm file1

#11) mkdir: Make directory

• Syntax: mkdir [OPTION] directory
• Example: Create directory called dir1
  • $ mkdir dir1

#12) rmdir: Remove a directory

• Syntax: rmdir [OPTION] directory
• Example: Create empty files called ‘file1’ and ‘file2’
  • $ rmdir dir1

#13) cd: Change directory

• Syntax: cd [OPTION] directory
• Example: Change working directory to dir1
  • $ cd dir1

#14) pwd: Print the present working directory

• Syntax: pwd [OPTION]
• Example: Print ‘dir1’ if a current working directory is dir1
  • $ pwd

#15) ls: List directory contents

• Syntax: ls [OPTION] [FILE]
• Example: list all (including hidden files) directory contents, in long format, sorted by time,
  • $ ls -alt

#16) which: Locate a command

• Syntax: which [-a] filename
• Example: List all paths from where ‘cat’ can run
  • $ which -a cat

#17) man: Interface for working with the online reference manuals.

• Syntax: man [-s section] item
• Example: Show manual page for the ‘cat’ command
  • $ man cat

#18) su: Change user-id or become super-user.

• Syntax: su [options] [username]
• Example: Change user-id to ‘user1’ (if it exists)
  • $ su user1

#19) sudo: Execute a command as some other user or super-user

#20) find: Used to search for files and directories as mentioned in the ‘expression’

• Syntax: find [starting-point] [expression]
• Example: In ‘/usr’ folder, find character device files, of name ‘backup’
  • $ find /usr -type c -name backup

#21) du: Estimate disk usage is blocks

• Syntax: du [options] [file]
• Example: Show number of blocks occupied by files in the current directory
  • $ du

#22) df: Show number of free blocks for mounted file system

• Syntax: df [options] [file]
• Example: Show number of free blocks in local file systems
  • $ df -l
  • $ df -h