What does " 2>&1 " mean? (stackoverflow.com)

Article summary

The article explains the meaning of the command '2>&1' in Unix-based systems, which redirects the standard error (stderr) to the standard output (stdout). This is useful for combining the output of a command into a single stream, making it easier to process or log. The article also discusses the use of file descriptors and redirection operators in shell scripting. The command is commonly used in shell scripts and command-line interfaces to handle errors and output.

Main themes

• Unix shell scripting
• File descriptors
• Redirection operators
• Error handling
• Shell commands
• Output management

What commenters say

• The use of '2>&1' is a common and useful technique for handling errors and output in shell scripts.
• The command is not unique to Bash, but is a feature of POSIX-compliant shells.
• Understanding the underlying Unix syscall API, such as the dup2 function, can help clarify how file descriptors and redirection work.
• Some commenters find the syntax intuitive, while others suggest alternative approaches or find it confusing.
• The ability to redirect specific file descriptors into other commands is a powerful feature of shell scripting.
• The use of '2>&1' is not limited to simple error handling, but can be used in complex shell scripts to control output and logging.
• Alternative approaches, such as using the '>&' operator or the 'dup2' function, can achieve similar results.
• The discussion highlights the importance of understanding the basics of shell scripting and file descriptors to effectively use commands like '2>&1'.