scala(1) - f30

1scala(1)                         USER COMMANDS                        scala(1)
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NAME

6       scala - Run code in the Scala 2 language
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SYNOPSIS

9       scala  [ <option> ]... [ <torun> <argument>... ]
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PARAMETERS

12       <compiler-option>
13              Any scalac option.  See scalac(1).
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15       -howtorun:<how>
16              How  to execute <torun>, if it is present. Options for <how> are
17              guess (the default), script, and object.
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19       -i     Requests that a file be pre-loaded.  It is only  meaningful  for
20              interactive shells.
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22       -e     Requests that its argument be executed as Scala code.
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24       -savecompiled
25              Save this compiled version of scripts in order to speed up later
26              executions of the same script.  When running a script, save  the
27              compiled  version  of in a file with the same name as the script
28              but with an extension of .jar.  On subsequent runs of  the  same
29              script,  the  pre-compiled .jar file will be used if it is newer
30              than the script file.
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32       -nocompdaemon
33              Do not use the fsc offline compiler.
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35       -Dproperty=value
36              Set a Java system property.  If no value is specified, then  the
37              property is set to the empty string.
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39       <torun>
40              A top-level object or a script file to run.
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42       <argument>
43              An arguments to pass to <torun>.
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DESCRIPTION

46       The  scala  utility  runs  Scala code using a Java runtime environment.
47       The Scala code to run is specified in one of three ways:
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49          1.  With no arguments specified, a Scala shell starts and reads com‐
50              mands interactively.
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52          2.  With  -howtorun:object  specified, the fully qualified name of a
53              top-level Scala object may be specified.  The object should pre‐
54              viously have been compiled using scalac(1).
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56          3.  With  -howtorun:script  specified,  a file containing Scala code
57              may be specified.
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59       If -howtorun: is left as the default (guess), then  the  scala  command
60       will  check  whether  a file of the specified name exists.  If it does,
61       then it will treat it as a script file; if it does not,  then  it  will
62       treat it as the name of an object.
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64       In all three cases, arbitrary scalac options may be specified. The most
65       common option is to specify a classpath with -classpath,  but  see  the
66       scalac(1) page for full details.
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68       If  an object is specified to run, then that object must be a top-level
69       Scala object with the specified name.  The object must define a  method
70       main with the following signature:
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72       def main(args: Array[String]): Unit
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74       The  method must return a Unit value, and it must accept a String array
75       as a parameter.  All arguments specified on the command  line  will  be
76       passed as arguments to the main method.
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78       If  a  script  file  is specified to run, then the file is read and all
79       Scala statements and declarations in the file are processed  in  order.
80       Any arguments specified will be available via the argsvariable.
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82       Script  files  may  have an optional header that is ignored if present.
83       There are two ways to format the header: either beginning with  #!  and
84       ending with !#, or beginning with ::#! and ending with ::!#.
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86       Such  a header must have each header boundary start at the beginning of
87       a line.  Headers can be used to make stand-alone script files, as shown
88       in the examples below.
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90       If  scala  is  run  from  an sbaz(1) directory, then it will add to its
91       classpath any jars installed in the lib directory of  the  sbaz  direc‐
92       tory.   Additionally,  if no -classpath option is specified, then scala
93       will add ".", the current directory, to the end of the classpath.
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OPTIONS

96       If any compiler options are specified, they must be first in  the  com‐
97       mand  line  and must be followed by a bare hypen ("-") character. If no
98       arguments are specified after the optional compiler arguments, then  an
99       interactive Scala shell is started.  Otherwise, either a script file is
100       run, or a pre-compiled Scala object is run.  It is possible to  distin‐
101       guish  the last two cases by using an explicit -object or -script flag,
102       but usually the program can guess correctly.
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ENVIRONMENT

105       JAVACMD
106              Specify the java command to be used for running the Scala  code.
107              Arguments  may be specified as part of the environment variable;
108              spaces, quotation marks, etc., will be passed  directly  to  the
109              shell for expansion.
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111       JAVA_HOME
112              Specify JDK/JRE home directory. This directory is used to locate
113              the java command unless JAVACMD variable set.
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115       JAVA_OPTS
116              Specify the options to be passed to the java command defined  by
117              JAVACMD.
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119              With  Java 1.5 (or newer) one may for example configure the mem‐
120              ory usage of the JVM  as  follows:  JAVA_OPTS="-Xmx512M  -Xms16M
121              -Xss16M"
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123              With  GNU  Java one may configure the memory usage of the GIJ as
124              follows: JAVA_OPTS="--mx512m --ms16m"
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EXAMPLES

127       Here are some examples of running Scala code:
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129       Execute a Scala program generated in the current directory
130              scala hello.HelloWorld
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132       Execute a Scala program generated in a user-defined directory classes
133              scala -classpath classes hello.HelloWorld
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135       Execute a Scala program using a user-defined java command
136              env  JAVACMD=/usr/local/bin/cacao   scala   -classpath   classes
137              hello.HelloWorld
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139       Execute a Scala program using JVM options
140              env JAVACMD=java JAVA_OPTS="-Dmsg=hello -enableassertions" scala
141              -classpath classes hello.HelloWorld
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143       Here is a complete Scala script for Unix:
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145       #!/bin/sh
146       exec scala "$0" "$@"
147       !#
148       Console.println("Hello, world!")
149       argv.toList foreach Console.println
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151       Here is a complete Scala script for MS Windows:
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153       ::#!
154       @echo off
155       call scala %0 %*
156       goto :eof
157       ::!#
158       Console.println("Hello, world!")
159       argv.toList foreach Console.println
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161       If you want to use the compilation cache to speed  up  multiple  execu‐
162       tions of the script, then add -savecompiled to the scala command:
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164       #!/bin/sh
165       exec scala -savecompiled "$0" "$@"
166       !#
167       Console.println("Hello, world!")
168       argv.toList foreach Console.println
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EXIT STATUS

171       The  scala  command returns a zero exit status if it succeeds. Non zero
172       is returned in case of any error.  If a script or top-level  object  is
173       executed  and  returns  a value, then that return value is passed on to
174       scala.
175

AUTHOR

177       Written by Martin Odersky and other members of the Scala team.
178

REPORTING BUGS

180       Report bugs to https://issues.scala-lang.org/.
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COPYRIGHT

183       This is  open-source  software,  available  to  you  under  a  BSD-like
184       license.  See  accomponying  "copyright"  or "LICENSE" file for copying
185       conditions. There is NO warranty; not even for MERCHANTABILITY or  FIT‐
186       NESS FOR A PARTICULAR PURPOSE.
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