errno

Lookup errno description by name or code

$ errno [name|code]

$ errno --list

$ errno --search [text]

$ errno --search-all-locales [text]

errno [number]

number
    Optional. A numeric error code. If provided, errno will attempt to find and print the corresponding error name.
If not provided, errno will print a list of errno names with values.

The errno command in Linux is a simple utility that displays the symbolic name of a given error number, as defined in the system's error code header files (typically errno.h). This is helpful for debugging and understanding the meaning of error codes returned by system calls or library functions. The command essentially acts as a lookup table, mapping numeric error values to their corresponding symbolic names, such as EACCES (Permission denied) or ENOENT (No such file or directory). It simplifies error analysis by translating raw numeric codes into human-readable, meaningful names. It's a useful tool for developers and system administrators when troubleshooting programs and identifying the root cause of errors.

When invoked without arguments, errno will print a list of errno names with values. errno {number} will translate that number to the errno name.

The exact set of error codes and their meanings can vary slightly between different Linux distributions and kernel versions. The values are dependent on the system header files.

To find the error name for error code 2:
errno 2

This might output something like: ENOENT

The command is most often used in interactive debugging, but can also be used in scripts to translate a return code to a text representation.

The errno command has been a standard utility in Unix-like operating systems for a long time. It serves to access the meaning of the global variable errno as defined in the C standard library. It's primary purpose is to translate error codes generated by the system into human understandable names.

strerror(3), perror(3)