Week 3 (not filtered).docx

**Study Notes on Shell Redirection** **1. Introduction to Redirection** Shell redirection allows changing where commands read input and send output, applying to all commands run by the shell. **1.1 Redirection of Input and Output** - Input and output can be redirected to or from a file using \...

**Study Notes on Shell Redirection** **1. Introduction to Redirection** Shell redirection allows changing where commands read input and send output, applying to all commands run by the shell. **1.1 Redirection of Input and Output** - Input and output can be redirected to or from a file using \'\\' or to or from a program using \'\|\'. **2. Output Redirection - Standard Output and Standard Error** - Commands produce standard output and standard error which can be redirected separately. **2.1 Standard Output (stdout)** - Standard output can be redirected to a file or another command using \'\>\'. **2.2 Standard Error (stderr)** - Standard error is output in case of an error and can be redirected using \'2\>\'. **3. Output Redirection Syntax with \>** - The \'\>\' symbol indicates output redirection to a file, truncating it if it exists. - Space before \'\>\' is required, and the space after is optional. **3.1 Four Rules for Output Redirection** - Redirection is done before running the command. - Redirection only affects visible output. - Redirection goes to one place. - By default, only standard output is redirected. **3.7 Output Redirection: Appending to Files using \>\>** - \'\>\>\' appends output to a file instead of truncating it. **4. Additional Notes on Redirection** - Avoid redirecting both stdout and stderr to the same file to prevent overwriting. - Use \'2\>&1\' to redirect both stdout and stderr safely into a single file. **5. Input Redirection - Standard Input** - Commands read input from files or standard input (stdin) if no file names are given. - Redirection using \'\