Command Redirection and Pipeing in linux

Unix/Linux command normally takes input from keyboard and display output to computer screen. something while doing some complex scripting or admin tasks, need arises to take input from a file or take input from some other command and output to a file.here is where we resort to command redirection and piping in Linux command.

• Character ">" is used to redirect output of command to a file, if file already exist replace it.

          ls -l > Outputfile.txt

          To append the output to a existing file we can use “>>”

           date >> Outputfile.txt

•  Character “<” is used to pass input from a file to a command

           grep “myword” < Imputfile.txt

•   To redirect standard error to a file using “2>”

           Mycommand 2> errorfile.txt

• We can also direct one command’s output to another command by using character “|” (pipe).

           ls -l | grep “myword” | sort -r

 In the above example firsts requests a “ls –l” command is being redirected using “|” pipe to                          “grep myword” command to search the "myword" from previous command output and ultimately      output is redirected to “sort -r” command to sort the result.