I/O Best Practices
- Always redirect errors to logs.
- Use >> instead of > to avoid data loss.
- Use pipes to chain commands efficiently.
- Keep logs organized and readable.
Shell Script · I/O Redirection
Shell Scripting · Lesson 19
I/O Redirection
Input output redirection in Linux shell. Use > >> and pipes. Redirect errors and logs. Important concept for automation.
What is I/O Redirection?
I/O redirection allows you to control where input comes from and where output goes. By default, commands read from keyboard and write to terminal.
Types of Redirection
- Standard Input (stdin) – 0
- Standard Output (stdout) – 1
- Standard Error (stderr) – 2
Redirection Examples
1. Standard Output Redirection ( > )
Redirect command output to a file (overwrite).
terminal — bash
ioecho "Hello World" > output.txt
cat output.txt
2. Append Output ( >> )
Append output to an existing file.
terminal — bash
ioecho "Line 1" > file.txt
echo "Line 2" >> file.txt
cat file.txt
3. Standard Error Redirection (2>)
Redirect error messages to a file.
terminal — bash
iols /wrongpath 2> error.log
4. Redirect Both Output and Error
Redirect both stdout and stderr.
terminal — bash
iocommand > all.log 2>&1
5. Using Pipe ( | )
Send output of one command as input to another.
terminal — bash
iols -l | grep ".txt"
Best Practices
Practice Task – I/O Redirection
- Redirect command output to a file.
- Redirect error messages to a log file.
- Use pipe to filter output.
Next lesson: File Permissions & Ownership