Unix - Shell Input Output Redirections

In Unix, shell input/output redirections are a mechanism for manipulating the input and output of a command or a shell script. They allow you to redirect the standard input, standard output, and standard error of a command or script to different sources or destinations.

The following are some of the most common input/output redirection operators in Unix:

">" - This operator redirects the standard output of a command to a file. For example, the command "ls > file.txt" will redirect the output of the "ls" command to a file named "file.txt".

">>" - This operator appends the standard output of a command to the end of a file, rather than overwriting the file. For example, the command "echo 'Hello' >> file.txt" will append the string "Hello" to the end of the file "file.txt".

"<" - This operator redirects the standard input of a command to come from a file. For example, the command "sort < file.txt" will read the contents of "file.txt" as input to the "sort" command.

"2>" - This operator redirects the standard error output of a command to a file. For example, the command "ls /nonexistent 2> error.txt" will redirect the error output of the "ls" command to a file named "error.txt".

"&>" - This operator redirects both standard output and standard error output of a command to a file. For example, the command "ls /nonexistent &> output.txt" will redirect both the standard output and error output of the "ls" command to a file named "output.txt".

Shell input/output redirections are useful for manipulating the output of commands, capturing error messages, and combining the output of multiple commands. By using input/output redirections, you can build powerful Unix scripts that automate tasks and streamline your workflow.