.Dd Apr 2, 2007
.Dt JRUBY(1) "" ""
.\".Dt JRUBY 1
.Os UNIX
.Sh NAME
.Nm jruby
.Nd Interpreted object-oriented scripting language
.Sh SYNOPSIS
.Nm
.Op Fl \-copyright
.Op Fl \-version
.Op Fl Sacdlnpswvy
.Op Fl 0 Ns Op Ar octal
.Op Fl C Ar directory
.Op Fl F Ar pattern
.Op Fl I Ar directory
.Op Fl K Ar c
.Op Fl T Ns Op Ar level
.Op Fl e Ar command
.Op Fl i Ns Op Ar extension
.Op Fl r Ar library
.Op Fl x Ns Op Ar directory
.Op Fl \-
.Op Ar program_file
.Op Ar argument ...
.Sh DESCRIPTION
Jruby is a 100% pure-Java implementation of Ruby, an interpreted
scripting language for quick and easy object-oriented programming.  It
has many features to process text files and to do system management
tasks (as in Perl).  It is simple, straight-forward, and extensible.
.Sh OPTIONS
Ruby interpreter accepts following command-line options (switches).
They are quite similar to those of
.Xr perl 1 .
.Bl -tag -width "1234567890123" -compact
.Pp
.It Fl \-copyright
Prints the copyright notice.
.Pp
.It Fl \-version
Prints the version of Ruby interpreter.
.Pp
.It Fl 0 Ns Op Ar octal
(The digit
.Dq zero . )
Specifies the input record separator
.Pf ( Li "$/" )
as an octal number. If no digit is given, the null character is taken
as the separator.  Other switches may follow the digits.
.Fl 00
turns Ruby into paragraph mode.
.Fl 0777
makes Ruby read whole file at once as a single string since there is
no legal character with that value.
.Pp
.It Fl C Ar directory
Causes Ruby to switch to the directory.
.Pp
.It Fl F Ar pattern
Specifies input field separator
.Pf ( Li "$;" ) .
.Pp
.It Fl I Ar directory
Used to tell Ruby where to load the library scripts.  Directory path
will be added to the load-path variable
.Pf ( Li "$:" ) .
.Pp
.It Fl K Ar kcode
Specifies KANJI (Japanese) encoding.
.Pp
.It Fl S
Makes Ruby use the
.Ev PATH
environment variable to search for script, unless if its name begins
with a slash.  This is used to emulate
.Li #!
on machines that don't support it, in the following manner:
.Bd -literal -offset indent
#! /usr/local/bin/ruby
# This line makes the next one a comment in Ruby \e
  exec /usr/local/bin/ruby \-S $0 $*
.Ed
.Pp
.It Fl T Ns Op Ar level
Turns on taint checks at the specified level (default 1).
.Pp
.It Fl a
Turns on auto-split mode when used with
.Fl n
or
.Fl p .
In auto-split mode, Ruby executes
.Dl $F = $_.split
at beginning of each loop.
.Pp
.It Fl c
Causes Ruby to check the syntax of the script and exit without
executing. If there are no syntax errors, Ruby will print
.Dq Syntax OK
to the standard output.
.Pp
.It Fl d
.It Fl \-debug
Turns on debug mode.
.Li "$DEBUG"
will be set to true.
.Pp
.It Fl e Ar command
Specifies script from command-line while telling Ruby not to search
the rest of arguments for a script file name.
.Pp
.It Fl h
.It Fl \-help
Prints a summary of the options.
.Pp
.It Fl i Ar extension
Specifies in-place-edit mode.  The extension, if specified, is added
to old file name to make a backup copy.  For example:
.Bd -literal -offset indent
% echo matz > /tmp/junk
% cat /tmp/junk
matz
% ruby \-p \-i.bak \-e '$_.upcase!' /tmp/junk
% cat /tmp/junk
MATZ
% cat /tmp/junk.bak
matz
.Ed
.Pp
.It Fl l
(The lowercase letter
.Dq ell . )
Enables automatic line-ending processing, which means to firstly set
.Li "$\e"
to the value of
.Li "$/" ,
and secondly chops every line read using
.Li chop! .
.Pp
.It Fl n
Causes Ruby to assume the following loop around your script, which
makes it iterate over file name arguments somewhat like
.Nm sed
.Fl n
or
.Nm awk .
.Bd -literal -offset indent
while gets
  ...
end
.Ed
.Pp
.It Fl p
Acts mostly same as \-n switch, but print the value of variable
.Li "$_"
at the each end of the loop.  For example:
.Bd -literal -offset indent
% echo matz | ruby \-p \-e '$_.tr! "a-z", "A-Z"'
MATZ
.Ed
.Pp
.It Fl r Ar library
Causes Ruby to load the library using require.  It is useful when using
.Fl n
or
.Fl p .
.Pp
.It Fl s
Enables some switch parsing for switches after script name but before
any file name arguments (or before a
.Fl \- ) .
Any switches found there are removed from
.Li ARGV
and set the corresponding variable in the script.  For example:
.Bd -literal -offset indent
#! /usr/local/bin/ruby \-s
# prints "true" if invoked with `\-xyz' switch.
print "true\en" if $xyz
.Ed
.Pp
On some systems
.Li "$0"
does not always contain the full pathname, so you need the
.Fl S
switch to tell Ruby to search for the script if necessary.  To handle
embedded spaces or such.  A better construct than
.Li "$*"
would be
.Li ${1+"$@"} ,
but it does not work if the script is being interpreted by
.Xr csh 1 .
.Pp
.It Fl v
.It Fl \-verbose
Enables verbose mode.  Ruby will print its version at the beginning,
and set the variable
.Li "$VERBOSE"
to true.  Some methods print extra messages if this variable is true.
If this switch is given, and no other switches are present, Ruby quits
after printing its version.
.Pp
.It Fl w
Enables verbose mode without printing version message at the
beginning.  It sets the
.Li "$VERBOSE"
variable to true.
.Pp
.It Fl x Ns Op Ar directory
Tells Ruby that the script is embedded in a message.  Leading garbage
will be discarded until the first that starts with
.Dq #!
and contains the string,
.Dq ruby .
Any meaningful switches on that line will applied.  The end of script
must be specified with either
.Li EOF ,
.Li "^D" ( Li "control-D" ) ,
.Li "^Z" ( Li "control-Z" ) ,
or reserved word
.Li __END__ .
If the directory name is specified, Ruby will switch to that directory
before executing script.
.Pp
.It Fl y
.It Fl \-yydebug
Turns on compiler debug mode.  Ruby will print a bunch of internal
state messages during compiling scripts.  You don't have to specify
this switch, unless you are going to debug the Ruby interpreter.
.El
.Pp