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errno:tldr:e4acb
The command "errno" is used to retrieve the error number associated with the last system call that encountered an error. The variable "${select}" is likely a placeholder for a specific system call.
In Unix-like systems, system calls can return an error code to indicate various types of errors. The "errno" command allows you to access this error code and determine the type of error that occurred. By supplying "${select}" as an argument to "errno", you are most likely trying to retrieve the error number associated with a system call called "select".
The "select" system call is often used for multiplexing I/O operations, allowing a program to monitor multiple file descriptors for events like data availability, connection requests, or errors. If the "select" system call encounters an error, the error number can be retrieved using "errno" to understand the cause of the failure.