# A practical cheatsheet to mastering I/O redirection in Linux.

# Learn how to redirect stdout and stderr to files,

# silence output, and combine streams with '>' and '2>&1'.

# ----- Linux I/O Redirection Cheatsheet -----

# Redirect standard output (stdout) to a file:

# WARNING: '>' OVERWRITES the file if it exists!

xinit@localhost:~$ ls -l > files_list.txt

# Redirect stdout and APPEND to a file:

# '>>' adds new content to the end of the file.

xinit@localhost:~$ echo "New log entry" >> application.log

# Redirect ONLY errors (stderr) to a file:

# Useful for separating logs from errors.

xinit@localhost:~$ ./script.sh 2> error.log

# Redirect stdout to one file, and stderr to another:

xinit@localhost:~$ ./script.sh > output.log 2> error.log

# ----- Combining Streams -----

# Redirect BOTH stdout and stderr to the same file (OVERWRITE):

# '2>&1' means "redirect stderr (2) to the same place as stdout (1)".

xinit@localhost:~$ ./script.sh > script.log 2>&1

# Redirect BOTH stdout and stderr and APPEND to the same file:

# This is the perfect way to log everything from a script.

xinit@localhost:~$ ./script.sh >> script.log 2>&1

# ----- Pro Tricks -----

# Silence all output (send it to "the void"):

# Useful for cron jobs when you don't need any output.

xinit@localhost:~$ ./script.sh > /dev/null 2>&1

# Use a pipe '|' to send the output of one command

# as the input for another command (e.g., grep):

xinit@localhost:~$ cat /var/log/syslog | grep 'error'