Ruby Command Line Options

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Ruby is generally run from the command line in the following way:

$ ruby [ options ] [.] [ programfile ] [ arguments ... ]

The interpreter can be invoked with any of the following options to control the environment and behavior of the interpreter.

OptionDescription
-a Used with -n or -p to split each line. Check -n and -p options.
-c Checks syntax only, without executing program.
-C dir Changes directory before executing (equivalent to -X).
-d Enables debug mode (equivalent to -debug).
-F patSpecifies pat as the default separator pattern ($;) used by split.
-e progSpecifies prog as the program from the command line. Specify multiple -e options for multiline programs.
-h Displays an overview of command-line options.
-i [ ext] Overwrites the file contents with program output. The original file is saved with the extension ext. If ext isn't specified, the original file is deleted.
-I dir Adds dir as the directory for loading libraries.
-K [ kcode]Specifies the multibyte character set code (e or E for EUC (extended Unix code); s or S for SJIS (Shift-JIS); u or U for UTF-8; and a, A, n, or N for ASCII).
-l Enables automatic line-end processing. Chops a newline from input lines and appends a newline to output lines.
-n Places code within an input loop (as in while gets; ... end).
-0[ octal]Sets default record separator ($/) as an octal. Defaults to \0 if octal not specified.
-p Places code within an input loop. Writes $_ for each iteration.
-r lib Uses require to load lib as a library before executing.
-s Interprets any arguments between the program name and filename arguments fitting the pattern -xxx as a switch and defines the corresponding variable.
-T [level] Sets the level for tainting checks (1 if level not specified).
-v Displays version and enables verbose mode
-w Enables verbose mode. If programfile not specified, reads from STDIN.
-x [dir] Strips text before #!ruby line. Changes directory to dir before executing if dir is specified.
-X dir Changes directory before executing (equivalent to -C).
-y Enables parser debug mode.
--copyright Displays copyright notice.
--debug Enables debug mode (equivalent to -d).
--help Displays an overview of command-line options (equivalent to -h).
--version Displays version.
--verbose Enables verbose mode (equivalent to -v). Sets $VERBOSE to true
--yydebug Enables parser debug mode (equivalent to -y).

Single character command-line options can be combined. The following two lines express the same meaning:

$ruby -ne 'print if /Ruby/' /usr/share/bin

$ruby -n -e 'print if /Ruby/' /usr/share/bin


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