Linux getopt Command

In this tutorial we learn how to use getopt commmand in Linux. getopt command is getopt - parse command options (enhanced)

What is Linux getopt Command?

In this tutorial we learn how to use getopt command in Linux. getopt command is getopt - parse command options (enhanced)

getopt Syntax

       getopt optstring parameters
       getopt [options] [--] optstring parameters
       getopt [options] -o|--options optstring [options] [--] parameters
       The  parameters getopt is called with can be divided into two parts: options which modify the way getopt will do the parsing (the options and the optstring in the SYNOPSIS), and the parameters which
       If  the  environment  variable GETOPT_COMPATIBLE is set, or if the first parameter is not an option (does not start with a '-', the first format in the SYNOPSIS), getopt will generate output that is
       compatible with that of other versions of getopt(1).  It will still do parameter shuffling and recognize optional arguments (see section COMPATIBILITY for more information).
       Traditional implementations of getopt(1) are unable to cope with whitespace and other (shell-specific) special characters in arguments and non-option parameters.  To solve this problem, this  imple‐
       getopt in a way that is no longer compatible with other versions (the second or third format in the SYNOPSIS).  To determine whether this enhanced version of getopt(1) is installed, a  special  test
              The name that will be used by the getopt(3) routines when it reports errors.  Note that errors of getopt(1) are still reported as coming from getopt.
              The short (one-character) options to be recognized.  If this option is not found, the first parameter of getopt that does not start with a '-' (and is not an option argument) is used  as  the
              Disable error reporting by getopt(3).
              Do not generate normal output.  Errors are still reported by getopt(3), unless you also use -q.
              Test if your getopt(1) is this enhanced version or an old version.  This generates no output, and sets the error status to 4.  Other implementations of getopt(1), and this version if the  en‐
              Do not quote the output.  Note that whitespace and special (shell-dependent) characters can cause havoc in this mode (like they do with other getopt(1) implementations).
       This  section  specifies the format of the second part of the parameters of getopt (the parameters in the SYNOPSIS).  The next section (OUTPUT) describes the output that is generated.  These parame‐
       list of getopt (see the EXAMPLES).  All parsing is done by the GNU getopt(3) routines.
       getopt(1) implementations do not support optional arguments.
       This version of getopt(1) is written to be as compatible as possible to other versions.  Usually you can just replace them with this version without any modifications, and with some advantages.
       If  the first character of the first parameter of getopt is not a '-', getopt goes into compatibility mode.  It will interpret its first parameter as the string of short options, and all other argu‐
       The environment variable GETOPT_COMPATIBLE forces getopt into compatibility mode.  Setting both this environment variable and POSIXLY_CORRECT offers  100%  compatibility  for  'difficult'  programs.
       getopt  returns  error  code 0 for successful parsing, 1 if getopt(3) returns errors, 2 if it does not understand its own parameters, 3 if an internal error occurs like out-of-memory, and 4 if it is
       Example scripts for (ba)sh and (t)csh are provided with the getopt(1) distribution, and are optionally installed in /usr/share/getopt/ or /usr/share/doc/ in the util-linux subdirectory.
              This environment variable is examined by the getopt(3) routines.  If it is set, parsing stops as soon as a parameter is found that is not an option or an option argument.  All  remaining  pa‐
              Forces getopt to use the first calling format as specified in the SYNOPSIS.
       getopt(3) can parse long options with optional arguments that are given an empty optional argument (but cannot do this for short options).  This getopt(1) treats optional arguments that are empty as
       bash(1), tcsh(1), getopt(3)
       The getopt command is part of the util-linux package and is available from Linux Kernel Archive ⟨https://www.kernel.org/pub/linux/utils/util-linux/⟩.

getopt Examples

getopt Command Manual / Help

We can use man and info command to see the manual page of getopt command.

getopt command also have --help option to show list of options.

To open man page for getopt command we can use command below. To exit man or info page you can press q.

man getopt

To open info page for getopt command we can use command below.

info getopt

To open help page from getopt command we can run command below.

getopt --help