Input and output redirection

Redirection operators

symbol	Description
'<'	input redirection
'>'	output redirection
'2>'	error redirection
'>>'	append redirection

Input redirection (<)

Instead of accepting input from standard i/p(Keyboard) we can change it to file

Example:-

• cat < myfile , will work same as cat myfile
• < indicates take input from myfile and display output on standard output device

Output redirection (>)

To redirect output for some file use >

Example:-

• cat < myfile > newfile
• ls -l > newfile

NOTE - if you are redirecting output to file which has already content, then the content will be overridden

Append redirection (>>)

to append output to given file

Example:-

• cat file1 >> result
• ls -l >> result

Error redirection (2>)

if you want to redirect error output to file then we can use 2>

Example:-

• cat abc.txt > pqr.txt 2> err.txt if file abc.txt exists then the content copied to pqr.txt else its a error, the error output will be sent to err.txt

file permission

r w x | r w x | r w x

• first 3 characters ( 1st to 3rd) - user related permission
• 4th to 6th character - group related permission
• 7th to 9th character - others related permission