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</script></head><body><div id="package-header"><ul class="links" id="page-menu"><li><a href="index.html">Contents</a></li><li><a href="doc-index.html">Index</a></li></ul><p class="caption">process-1.1.0.1: Process libraries</p></div><div id="content"><div id="module-header"><table class="info"><tr><th>Portability</th><td>non-portable (requires concurrency)</td></tr><tr><th>Stability</th><td>experimental</td></tr><tr><th>Maintainer</th><td>libraries@haskell.org</td></tr><tr><th>Safe Haskell</th><td>Trustworthy</td></tr></table><p class="caption">System.Process</p></div><div id="table-of-contents"><p class="caption">Contents</p><ul><li><a href="#g:1">Running sub-processes
</a><ul><li><a href="#g:2">Specific variants of createProcess
</a></li></ul></li><li><a href="#g:3">Process completion
</a></li></ul></div><div id="description"><p class="caption">Description</p><div class="doc"><p>Operations for creating and interacting with sub-processes.
</p></div></div><div id="synopsis"><p id="control.syn" class="caption expander" onclick="toggleSection('syn')">Synopsis</p><ul id="section.syn" class="hide" onclick="toggleSection('syn')"><li class="src short"><a href="#v:createProcess">createProcess</a> :: <a href="System-Process.html#t:CreateProcess">CreateProcess</a> -> <a href="../base-4.5.1.0/System-IO.html#t:IO">IO</a> (<a href="../base-4.5.1.0/Data-Maybe.html#t:Maybe">Maybe</a> <a href="../base-4.5.1.0/GHC-IO-Handle.html#t:Handle">Handle</a>, <a href="../base-4.5.1.0/Data-Maybe.html#t:Maybe">Maybe</a> <a href="../base-4.5.1.0/GHC-IO-Handle.html#t:Handle">Handle</a>, <a href="../base-4.5.1.0/Data-Maybe.html#t:Maybe">Maybe</a> <a href="../base-4.5.1.0/GHC-IO-Handle.html#t:Handle">Handle</a>, <a href="System-Process.html#t:ProcessHandle">ProcessHandle</a>)</li><li class="src short"><a href="#v:shell">shell</a> :: <a href="../base-4.5.1.0/Data-String.html#t:String">String</a> -> <a href="System-Process.html#t:CreateProcess">CreateProcess</a></li><li class="src short"><a href="#v:proc">proc</a> :: <a href="../base-4.5.1.0/System-IO.html#t:FilePath">FilePath</a> -> [<a href="../base-4.5.1.0/Data-String.html#t:String">String</a>] -> <a href="System-Process.html#t:CreateProcess">CreateProcess</a></li><li class="src short"><span class="keyword">data</span> <a href="#t:CreateProcess">CreateProcess</a> = <a href="#v:CreateProcess">CreateProcess</a> {<ul class="subs"><li><a href="#v:cmdspec">cmdspec</a> :: <a href="System-Process.html#t:CmdSpec">CmdSpec</a></li><li><a href="#v:cwd">cwd</a> :: <a href="../base-4.5.1.0/Data-Maybe.html#t:Maybe">Maybe</a> <a href="../base-4.5.1.0/System-IO.html#t:FilePath">FilePath</a></li><li><a href="#v:env">env</a> :: <a href="../base-4.5.1.0/Data-Maybe.html#t:Maybe">Maybe</a> [(<a href="../base-4.5.1.0/Data-String.html#t:String">String</a>, <a href="../base-4.5.1.0/Data-String.html#t:String">String</a>)]</li><li><a href="#v:std_in">std_in</a> :: <a href="System-Process.html#t:StdStream">StdStream</a></li><li><a href="#v:std_out">std_out</a> :: <a href="System-Process.html#t:StdStream">StdStream</a></li><li><a href="#v:std_err">std_err</a> :: <a href="System-Process.html#t:StdStream">StdStream</a></li><li><a href="#v:close_fds">close_fds</a> :: <a href="../base-4.5.1.0/Data-Bool.html#t:Bool">Bool</a></li><li><a href="#v:create_group">create_group</a> :: <a href="../base-4.5.1.0/Data-Bool.html#t:Bool">Bool</a></li></ul>}</li><li class="src short"><span class="keyword">data</span> <a href="#t:CmdSpec">CmdSpec</a> <ul class="subs"><li>= <a href="#v:ShellCommand">ShellCommand</a> <a href="../base-4.5.1.0/Data-String.html#t:String">String</a> </li><li>| <a href="#v:RawCommand">RawCommand</a> <a href="../base-4.5.1.0/System-IO.html#t:FilePath">FilePath</a> [<a href="../base-4.5.1.0/Data-String.html#t:String">String</a>] </li></ul></li><li class="src short"><span class="keyword">data</span> <a href="#t:StdStream">StdStream</a> <ul class="subs"><li>= <a href="#v:Inherit">Inherit</a> </li><li>| <a href="#v:UseHandle">UseHandle</a> <a href="../base-4.5.1.0/GHC-IO-Handle.html#t:Handle">Handle</a> </li><li>| <a href="#v:CreatePipe">CreatePipe</a> </li></ul></li><li class="src short"><span class="keyword">data</span> <a href="#t:ProcessHandle">ProcessHandle</a> </li><li class="src short"><a href="#v:runCommand">runCommand</a> :: <a href="../base-4.5.1.0/Data-String.html#t:String">String</a> -> <a href="../base-4.5.1.0/System-IO.html#t:IO">IO</a> <a href="System-Process.html#t:ProcessHandle">ProcessHandle</a></li><li class="src short"><a href="#v:runProcess">runProcess</a> :: <a href="../base-4.5.1.0/System-IO.html#t:FilePath">FilePath</a> -> [<a href="../base-4.5.1.0/Data-String.html#t:String">String</a>] -> <a href="../base-4.5.1.0/Data-Maybe.html#t:Maybe">Maybe</a> <a href="../base-4.5.1.0/System-IO.html#t:FilePath">FilePath</a> -> <a href="../base-4.5.1.0/Data-Maybe.html#t:Maybe">Maybe</a> [(<a href="../base-4.5.1.0/Data-String.html#t:String">String</a>, <a href="../base-4.5.1.0/Data-String.html#t:String">String</a>)] -> <a href="../base-4.5.1.0/Data-Maybe.html#t:Maybe">Maybe</a> <a href="../base-4.5.1.0/GHC-IO-Handle.html#t:Handle">Handle</a> -> <a href="../base-4.5.1.0/Data-Maybe.html#t:Maybe">Maybe</a> <a href="../base-4.5.1.0/GHC-IO-Handle.html#t:Handle">Handle</a> -> <a href="../base-4.5.1.0/Data-Maybe.html#t:Maybe">Maybe</a> <a href="../base-4.5.1.0/GHC-IO-Handle.html#t:Handle">Handle</a> -> <a href="../base-4.5.1.0/System-IO.html#t:IO">IO</a> <a href="System-Process.html#t:ProcessHandle">ProcessHandle</a></li><li class="src short"><a href="#v:runInteractiveCommand">runInteractiveCommand</a> :: <a href="../base-4.5.1.0/Data-String.html#t:String">String</a> -> <a href="../base-4.5.1.0/System-IO.html#t:IO">IO</a> (<a href="../base-4.5.1.0/GHC-IO-Handle.html#t:Handle">Handle</a>, <a href="../base-4.5.1.0/GHC-IO-Handle.html#t:Handle">Handle</a>, <a href="../base-4.5.1.0/GHC-IO-Handle.html#t:Handle">Handle</a>, <a href="System-Process.html#t:ProcessHandle">ProcessHandle</a>)</li><li class="src short"><a href="#v:runInteractiveProcess">runInteractiveProcess</a> :: <a href="../base-4.5.1.0/System-IO.html#t:FilePath">FilePath</a> -> [<a href="../base-4.5.1.0/Data-String.html#t:String">String</a>] -> <a href="../base-4.5.1.0/Data-Maybe.html#t:Maybe">Maybe</a> <a href="../base-4.5.1.0/System-IO.html#t:FilePath">FilePath</a> -> <a href="../base-4.5.1.0/Data-Maybe.html#t:Maybe">Maybe</a> [(<a href="../base-4.5.1.0/Data-String.html#t:String">String</a>, <a href="../base-4.5.1.0/Data-String.html#t:String">String</a>)] -> <a href="../base-4.5.1.0/System-IO.html#t:IO">IO</a> (<a href="../base-4.5.1.0/GHC-IO-Handle.html#t:Handle">Handle</a>, <a href="../base-4.5.1.0/GHC-IO-Handle.html#t:Handle">Handle</a>, <a href="../base-4.5.1.0/GHC-IO-Handle.html#t:Handle">Handle</a>, <a href="System-Process.html#t:ProcessHandle">ProcessHandle</a>)</li><li class="src short"><a href="#v:readProcess">readProcess</a> :: <a href="../base-4.5.1.0/System-IO.html#t:FilePath">FilePath</a> -> [<a href="../base-4.5.1.0/Data-String.html#t:String">String</a>] -> <a href="../base-4.5.1.0/Data-String.html#t:String">String</a> -> <a href="../base-4.5.1.0/System-IO.html#t:IO">IO</a> <a href="../base-4.5.1.0/Data-String.html#t:String">String</a></li><li class="src short"><a href="#v:readProcessWithExitCode">readProcessWithExitCode</a> :: <a href="../base-4.5.1.0/System-IO.html#t:FilePath">FilePath</a> -> [<a href="../base-4.5.1.0/Data-String.html#t:String">String</a>] -> <a href="../base-4.5.1.0/Data-String.html#t:String">String</a> -> <a href="../base-4.5.1.0/System-IO.html#t:IO">IO</a> (<a href="../base-4.5.1.0/System-Exit.html#t:ExitCode">ExitCode</a>, <a href="../base-4.5.1.0/Data-String.html#t:String">String</a>, <a href="../base-4.5.1.0/Data-String.html#t:String">String</a>)</li><li class="src short"><a href="#v:system">system</a> :: <a href="../base-4.5.1.0/Data-String.html#t:String">String</a> -> <a href="../base-4.5.1.0/System-IO.html#t:IO">IO</a> <a href="../base-4.5.1.0/System-Exit.html#t:ExitCode">ExitCode</a></li><li class="src short"><a href="#v:rawSystem">rawSystem</a> :: <a href="../base-4.5.1.0/Data-String.html#t:String">String</a> -> [<a href="../base-4.5.1.0/Data-String.html#t:String">String</a>] -> <a href="../base-4.5.1.0/System-IO.html#t:IO">IO</a> <a href="../base-4.5.1.0/System-Exit.html#t:ExitCode">ExitCode</a></li><li class="src short"><a href="#v:showCommandForUser">showCommandForUser</a> :: <a href="../base-4.5.1.0/System-IO.html#t:FilePath">FilePath</a> -> [<a href="../base-4.5.1.0/Data-String.html#t:String">String</a>] -> <a href="../base-4.5.1.0/Data-String.html#t:String">String</a></li><li class="src short"><a href="#v:waitForProcess">waitForProcess</a> :: <a href="System-Process.html#t:ProcessHandle">ProcessHandle</a> -> <a href="../base-4.5.1.0/System-IO.html#t:IO">IO</a> <a href="../base-4.5.1.0/System-Exit.html#t:ExitCode">ExitCode</a></li><li class="src short"><a href="#v:getProcessExitCode">getProcessExitCode</a> :: <a href="System-Process.html#t:ProcessHandle">ProcessHandle</a> -> <a href="../base-4.5.1.0/System-IO.html#t:IO">IO</a> (<a href="../base-4.5.1.0/Data-Maybe.html#t:Maybe">Maybe</a> <a href="../base-4.5.1.0/System-Exit.html#t:ExitCode">ExitCode</a>)</li><li class="src short"><a href="#v:terminateProcess">terminateProcess</a> :: <a href="System-Process.html#t:ProcessHandle">ProcessHandle</a> -> <a href="../base-4.5.1.0/System-IO.html#t:IO">IO</a> ()</li><li class="src short"><a href="#v:interruptProcessGroupOf">interruptProcessGroupOf</a> :: <a href="System-Process.html#t:ProcessHandle">ProcessHandle</a> -> <a href="../base-4.5.1.0/System-IO.html#t:IO">IO</a> ()</li></ul></div><div id="interface"><h1 id="g:1">Running sub-processes
</h1><div class="top"><p class="src"><a name="v:createProcess" class="def">createProcess</a> :: <a href="System-Process.html#t:CreateProcess">CreateProcess</a> -> <a href="../base-4.5.1.0/System-IO.html#t:IO">IO</a> (<a href="../base-4.5.1.0/Data-Maybe.html#t:Maybe">Maybe</a> <a href="../base-4.5.1.0/GHC-IO-Handle.html#t:Handle">Handle</a>, <a href="../base-4.5.1.0/Data-Maybe.html#t:Maybe">Maybe</a> <a href="../base-4.5.1.0/GHC-IO-Handle.html#t:Handle">Handle</a>, <a href="../base-4.5.1.0/Data-Maybe.html#t:Maybe">Maybe</a> <a href="../base-4.5.1.0/GHC-IO-Handle.html#t:Handle">Handle</a>, <a href="System-Process.html#t:ProcessHandle">ProcessHandle</a>)</p><div class="doc"><p>This is the most general way to spawn an external process. The
process can be a command line to be executed by a shell or a raw command
with a list of arguments. The stdin, stdout, and stderr streams of
the new process may individually be attached to new pipes, to existing
<code><a href="../base-4.5.1.0/GHC-IO-Handle.html#t:Handle">Handle</a></code>s, or just inherited from the parent (the default.)
</p><p>The details of how to create the process are passed in the
<code><a href="System-Process.html#t:CreateProcess">CreateProcess</a></code> record. To make it easier to construct a
<code><a href="System-Process.html#t:CreateProcess">CreateProcess</a></code>, the functions <code><a href="System-Process.html#v:proc">proc</a></code> and <code><a href="System-Process.html#v:shell">shell</a></code> are supplied that
fill in the fields with default values which can be overriden as
needed.
</p><p><code><a href="System-Process.html#v:createProcess">createProcess</a></code> returns <code>(mb_stdin_hdl, mb_stdout_hdl, mb_stderr_hdl, p)</code>,
where
</p><ul><li> if <code>std_in == CreatePipe</code>, then <code>mb_stdin_hdl</code> will be <code>Just h</code>,
where <code>h</code> is the write end of the pipe connected to the child
process's <code>stdin</code>.
</li><li> otherwise, <code>mb_stdin_hdl == Nothing</code>
</li></ul><p>Similarly for <code>mb_stdout_hdl</code> and <code>mb_stderr_hdl</code>.
</p><p>For example, to execute a simple <code>ls</code> command:
</p><pre> r <- createProcess (proc "ls" [])
</pre><p>To create a pipe from which to read the output of <code>ls</code>:
</p><pre> (_, Just hout, _, _) <-
createProcess (proc "ls" []){ std_out = CreatePipe }
</pre><p>To also set the directory in which to run <code>ls</code>:
</p><pre> (_, Just hout, _, _) <-
createProcess (proc "ls" []){ cwd = Just "\home\bob",
std_out = CreatePipe }
</pre></div></div><div class="top"><p class="src"><a name="v:shell" class="def">shell</a> :: <a href="../base-4.5.1.0/Data-String.html#t:String">String</a> -> <a href="System-Process.html#t:CreateProcess">CreateProcess</a></p><div class="doc"><p>Construct a <code><a href="System-Process.html#t:CreateProcess">CreateProcess</a></code> record for passing to <code><a href="System-Process.html#v:createProcess">createProcess</a></code>,
representing a command to be passed to the shell.
</p></div></div><div class="top"><p class="src"><a name="v:proc" class="def">proc</a> :: <a href="../base-4.5.1.0/System-IO.html#t:FilePath">FilePath</a> -> [<a href="../base-4.5.1.0/Data-String.html#t:String">String</a>] -> <a href="System-Process.html#t:CreateProcess">CreateProcess</a></p><div class="doc"><p>Construct a <code><a href="System-Process.html#t:CreateProcess">CreateProcess</a></code> record for passing to <code><a href="System-Process.html#v:createProcess">createProcess</a></code>,
representing a raw command with arguments.
</p></div></div><div class="top"><p class="src"><span class="keyword">data</span> <a name="t:CreateProcess" class="def">CreateProcess</a> </p><div class="subs constructors"><p class="caption">Constructors</p><table><tr><td class="src"><a name="v:CreateProcess" class="def">CreateProcess</a></td><td class="doc empty"> </td></tr><tr><td colspan="2"><div class="subs fields"><p class="caption">Fields</p><dl><dt class="src"><a name="v:cmdspec" class="def">cmdspec</a> :: <a href="System-Process.html#t:CmdSpec">CmdSpec</a></dt><dd class="doc"><p>Executable & arguments, or shell command
</p></dd><dt class="src"><a name="v:cwd" class="def">cwd</a> :: <a href="../base-4.5.1.0/Data-Maybe.html#t:Maybe">Maybe</a> <a href="../base-4.5.1.0/System-IO.html#t:FilePath">FilePath</a></dt><dd class="doc"><p>Optional path to the working directory for the new process
</p></dd><dt class="src"><a name="v:env" class="def">env</a> :: <a href="../base-4.5.1.0/Data-Maybe.html#t:Maybe">Maybe</a> [(<a href="../base-4.5.1.0/Data-String.html#t:String">String</a>, <a href="../base-4.5.1.0/Data-String.html#t:String">String</a>)]</dt><dd class="doc"><p>Optional environment (otherwise inherit from the current process)
</p></dd><dt class="src"><a name="v:std_in" class="def">std_in</a> :: <a href="System-Process.html#t:StdStream">StdStream</a></dt><dd class="doc"><p>How to determine stdin
</p></dd><dt class="src"><a name="v:std_out" class="def">std_out</a> :: <a href="System-Process.html#t:StdStream">StdStream</a></dt><dd class="doc"><p>How to determine stdout
</p></dd><dt class="src"><a name="v:std_err" class="def">std_err</a> :: <a href="System-Process.html#t:StdStream">StdStream</a></dt><dd class="doc"><p>How to determine stderr
</p></dd><dt class="src"><a name="v:close_fds" class="def">close_fds</a> :: <a href="../base-4.5.1.0/Data-Bool.html#t:Bool">Bool</a></dt><dd class="doc"><p>Close all file descriptors except stdin, stdout and stderr in the new process (on Windows, only works if std_in, std_out, and std_err are all Inherit)
</p></dd><dt class="src"><a name="v:create_group" class="def">create_group</a> :: <a href="../base-4.5.1.0/Data-Bool.html#t:Bool">Bool</a></dt><dd class="doc"><p>Create a new process group
</p></dd></dl><div class="clear"></div></div></td></tr></table></div></div><div class="top"><p class="src"><span class="keyword">data</span> <a name="t:CmdSpec" class="def">CmdSpec</a> </p><div class="subs constructors"><p class="caption">Constructors</p><table><tr><td class="src"><a name="v:ShellCommand" class="def">ShellCommand</a> <a href="../base-4.5.1.0/Data-String.html#t:String">String</a></td><td class="doc"><p>a command line to execute using the shell
</p></td></tr><tr><td class="src"><a name="v:RawCommand" class="def">RawCommand</a> <a href="../base-4.5.1.0/System-IO.html#t:FilePath">FilePath</a> [<a href="../base-4.5.1.0/Data-String.html#t:String">String</a>]</td><td class="doc"><p>the filename of an executable with a list of arguments
</p></td></tr></table></div></div><div class="top"><p class="src"><span class="keyword">data</span> <a name="t:StdStream" class="def">StdStream</a> </p><div class="subs constructors"><p class="caption">Constructors</p><table><tr><td class="src"><a name="v:Inherit" class="def">Inherit</a></td><td class="doc"><p>Inherit Handle from parent
</p></td></tr><tr><td class="src"><a name="v:UseHandle" class="def">UseHandle</a> <a href="../base-4.5.1.0/GHC-IO-Handle.html#t:Handle">Handle</a></td><td class="doc"><p>Use the supplied Handle
</p></td></tr><tr><td class="src"><a name="v:CreatePipe" class="def">CreatePipe</a></td><td class="doc"><p>Create a new pipe. The returned
<code>Handle</code> will use the default encoding
and newline translation mode (just
like <code>Handle</code>s created by <code>openFile</code>).
</p></td></tr></table></div></div><div class="top"><p class="src"><span class="keyword">data</span> <a name="t:ProcessHandle" class="def">ProcessHandle</a> </p></div><h2 id="g:2">Specific variants of createProcess
</h2><div class="top"><p class="src"><a name="v:runCommand" class="def">runCommand</a> :: <a href="../base-4.5.1.0/Data-String.html#t:String">String</a> -> <a href="../base-4.5.1.0/System-IO.html#t:IO">IO</a> <a href="System-Process.html#t:ProcessHandle">ProcessHandle</a></p><div class="doc"><p>Runs a command using the shell.
</p></div></div><div class="top"><p class="src"><a name="v:runProcess" class="def">runProcess</a></p><div class="subs arguments"><p class="caption">Arguments</p><table><tr><td class="src">:: <a href="../base-4.5.1.0/System-IO.html#t:FilePath">FilePath</a></td><td class="doc"><p>Filename of the executable
</p></td></tr><tr><td class="src">-> [<a href="../base-4.5.1.0/Data-String.html#t:String">String</a>]</td><td class="doc"><p>Arguments to pass to the executable
</p></td></tr><tr><td class="src">-> <a href="../base-4.5.1.0/Data-Maybe.html#t:Maybe">Maybe</a> <a href="../base-4.5.1.0/System-IO.html#t:FilePath">FilePath</a></td><td class="doc"><p>Optional path to the working directory
</p></td></tr><tr><td class="src">-> <a href="../base-4.5.1.0/Data-Maybe.html#t:Maybe">Maybe</a> [(<a href="../base-4.5.1.0/Data-String.html#t:String">String</a>, <a href="../base-4.5.1.0/Data-String.html#t:String">String</a>)]</td><td class="doc"><p>Optional environment (otherwise inherit)
</p></td></tr><tr><td class="src">-> <a href="../base-4.5.1.0/Data-Maybe.html#t:Maybe">Maybe</a> <a href="../base-4.5.1.0/GHC-IO-Handle.html#t:Handle">Handle</a></td><td class="doc"><p>Handle to use for <code>stdin</code> (Nothing => use existing <code>stdin</code>)
</p></td></tr><tr><td class="src">-> <a href="../base-4.5.1.0/Data-Maybe.html#t:Maybe">Maybe</a> <a href="../base-4.5.1.0/GHC-IO-Handle.html#t:Handle">Handle</a></td><td class="doc"><p>Handle to use for <code>stdout</code> (Nothing => use existing <code>stdout</code>)
</p></td></tr><tr><td class="src">-> <a href="../base-4.5.1.0/Data-Maybe.html#t:Maybe">Maybe</a> <a href="../base-4.5.1.0/GHC-IO-Handle.html#t:Handle">Handle</a></td><td class="doc"><p>Handle to use for <code>stderr</code> (Nothing => use existing <code>stderr</code>)
</p></td></tr><tr><td class="src">-> <a href="../base-4.5.1.0/System-IO.html#t:IO">IO</a> <a href="System-Process.html#t:ProcessHandle">ProcessHandle</a></td><td class="doc empty"> </td></tr></table></div><div class="doc"><p>Runs a raw command, optionally specifying <code><a href="../base-4.5.1.0/GHC-IO-Handle.html#t:Handle">Handle</a></code>s from which to
take the <code>stdin</code>, <code>stdout</code> and <code>stderr</code> channels for the new
process (otherwise these handles are inherited from the current
process).
</p><p>Any <code><a href="../base-4.5.1.0/GHC-IO-Handle.html#t:Handle">Handle</a></code>s passed to <code><a href="System-Process.html#v:runProcess">runProcess</a></code> are placed immediately in the
closed state.
</p><p>Note: consider using the more general <code><a href="System-Process.html#v:createProcess">createProcess</a></code> instead of
<code><a href="System-Process.html#v:runProcess">runProcess</a></code>.
</p></div></div><div class="top"><p class="src"><a name="v:runInteractiveCommand" class="def">runInteractiveCommand</a> :: <a href="../base-4.5.1.0/Data-String.html#t:String">String</a> -> <a href="../base-4.5.1.0/System-IO.html#t:IO">IO</a> (<a href="../base-4.5.1.0/GHC-IO-Handle.html#t:Handle">Handle</a>, <a href="../base-4.5.1.0/GHC-IO-Handle.html#t:Handle">Handle</a>, <a href="../base-4.5.1.0/GHC-IO-Handle.html#t:Handle">Handle</a>, <a href="System-Process.html#t:ProcessHandle">ProcessHandle</a>)</p><div class="doc"><p>Runs a command using the shell, and returns <code><a href="../base-4.5.1.0/GHC-IO-Handle.html#t:Handle">Handle</a></code>s that may
be used to communicate with the process via its <code>stdin</code>, <code>stdout</code>,
and <code>stderr</code> respectively. The <code><a href="../base-4.5.1.0/GHC-IO-Handle.html#t:Handle">Handle</a></code>s are initially in binary
mode; if you need them to be in text mode then use <code><a href="../base-4.5.1.0/GHC-IO-Handle.html#v:hSetBinaryMode">hSetBinaryMode</a></code>.
</p></div></div><div class="top"><p class="src"><a name="v:runInteractiveProcess" class="def">runInteractiveProcess</a></p><div class="subs arguments"><p class="caption">Arguments</p><table><tr><td class="src">:: <a href="../base-4.5.1.0/System-IO.html#t:FilePath">FilePath</a></td><td class="doc"><p>Filename of the executable
</p></td></tr><tr><td class="src">-> [<a href="../base-4.5.1.0/Data-String.html#t:String">String</a>]</td><td class="doc"><p>Arguments to pass to the executable
</p></td></tr><tr><td class="src">-> <a href="../base-4.5.1.0/Data-Maybe.html#t:Maybe">Maybe</a> <a href="../base-4.5.1.0/System-IO.html#t:FilePath">FilePath</a></td><td class="doc"><p>Optional path to the working directory
</p></td></tr><tr><td class="src">-> <a href="../base-4.5.1.0/Data-Maybe.html#t:Maybe">Maybe</a> [(<a href="../base-4.5.1.0/Data-String.html#t:String">String</a>, <a href="../base-4.5.1.0/Data-String.html#t:String">String</a>)]</td><td class="doc"><p>Optional environment (otherwise inherit)
</p></td></tr><tr><td class="src">-> <a href="../base-4.5.1.0/System-IO.html#t:IO">IO</a> (<a href="../base-4.5.1.0/GHC-IO-Handle.html#t:Handle">Handle</a>, <a href="../base-4.5.1.0/GHC-IO-Handle.html#t:Handle">Handle</a>, <a href="../base-4.5.1.0/GHC-IO-Handle.html#t:Handle">Handle</a>, <a href="System-Process.html#t:ProcessHandle">ProcessHandle</a>)</td><td class="doc empty"> </td></tr></table></div><div class="doc"><p>Runs a raw command, and returns <code><a href="../base-4.5.1.0/GHC-IO-Handle.html#t:Handle">Handle</a></code>s that may be used to communicate
with the process via its <code>stdin</code>, <code>stdout</code> and <code>stderr</code> respectively.
</p><p>For example, to start a process and feed a string to its stdin:
</p><pre> (inp,out,err,pid) <- runInteractiveProcess "..."
forkIO (hPutStr inp str)
</pre><p>The <code><a href="../base-4.5.1.0/GHC-IO-Handle.html#t:Handle">Handle</a></code>s are initially in binary mode; if you need them to be
in text mode then use <code><a href="../base-4.5.1.0/GHC-IO-Handle.html#v:hSetBinaryMode">hSetBinaryMode</a></code>.
</p></div></div><div class="top"><p class="src"><a name="v:readProcess" class="def">readProcess</a></p><div class="subs arguments"><p class="caption">Arguments</p><table><tr><td class="src">:: <a href="../base-4.5.1.0/System-IO.html#t:FilePath">FilePath</a></td><td class="doc"><p>command to run
</p></td></tr><tr><td class="src">-> [<a href="../base-4.5.1.0/Data-String.html#t:String">String</a>]</td><td class="doc"><p>any arguments
</p></td></tr><tr><td class="src">-> <a href="../base-4.5.1.0/Data-String.html#t:String">String</a></td><td class="doc"><p>standard input
</p></td></tr><tr><td class="src">-> <a href="../base-4.5.1.0/System-IO.html#t:IO">IO</a> <a href="../base-4.5.1.0/Data-String.html#t:String">String</a></td><td class="doc"><p>stdout
</p></td></tr></table></div><div class="doc"><p>readProcess forks an external process, reads its standard output
strictly, blocking until the process terminates, and returns the output
string.
</p><p>Output is returned strictly, so this is not suitable for
interactive applications.
</p><p>This function throws an <code><a href="../base-4.5.1.0/System-IO-Error.html#t:IOError">IOError</a></code> if the process <code><a href="../base-4.5.1.0/System-Exit.html#t:ExitCode">ExitCode</a></code> is
anything other than <code><a href="../base-4.5.1.0/System-Exit.html#v:ExitSuccess">ExitSuccess</a></code>.
</p><p>Users of this function should compile with <code>-threaded</code> if they
want other Haskell threads to keep running while waiting on
the result of readProcess.
</p><pre> > readProcess "date" [] []
"Thu Feb 7 10:03:39 PST 2008\n"
</pre><p>The arguments are:
</p><ul><li> The command to run, which must be in the $PATH, or an absolute path
</li><li> A list of separate command line arguments to the program
</li><li> A string to pass on the standard input to the program.
</li></ul></div></div><div class="top"><p class="src"><a name="v:readProcessWithExitCode" class="def">readProcessWithExitCode</a></p><div class="subs arguments"><p class="caption">Arguments</p><table><tr><td class="src">:: <a href="../base-4.5.1.0/System-IO.html#t:FilePath">FilePath</a></td><td class="doc"><p>command to run
</p></td></tr><tr><td class="src">-> [<a href="../base-4.5.1.0/Data-String.html#t:String">String</a>]</td><td class="doc"><p>any arguments
</p></td></tr><tr><td class="src">-> <a href="../base-4.5.1.0/Data-String.html#t:String">String</a></td><td class="doc"><p>standard input
</p></td></tr><tr><td class="src">-> <a href="../base-4.5.1.0/System-IO.html#t:IO">IO</a> (<a href="../base-4.5.1.0/System-Exit.html#t:ExitCode">ExitCode</a>, <a href="../base-4.5.1.0/Data-String.html#t:String">String</a>, <a href="../base-4.5.1.0/Data-String.html#t:String">String</a>)</td><td class="doc"><p>exitcode, stdout, stderr
</p></td></tr></table></div><div class="doc"><p>readProcessWithExitCode creates an external process, reads its
standard output and standard error strictly, waits until the process
terminates, and then returns the <code><a href="../base-4.5.1.0/System-Exit.html#t:ExitCode">ExitCode</a></code> of the process,
the standard output, and the standard error.
</p><p><code><a href="System-Process.html#v:readProcess">readProcess</a></code> and <code><a href="System-Process.html#v:readProcessWithExitCode">readProcessWithExitCode</a></code> are fairly simple wrappers
around <code><a href="System-Process.html#v:createProcess">createProcess</a></code>. Constructing variants of these functions is
quite easy: follow the link to the source code to see how
<code><a href="System-Process.html#v:readProcess">readProcess</a></code> is implemented.
</p></div></div><div class="top"><p class="src"><a name="v:system" class="def">system</a> :: <a href="../base-4.5.1.0/Data-String.html#t:String">String</a> -> <a href="../base-4.5.1.0/System-IO.html#t:IO">IO</a> <a href="../base-4.5.1.0/System-Exit.html#t:ExitCode">ExitCode</a></p><div class="doc"><p>Computation <code>system cmd</code> returns the exit code produced when the
operating system runs the shell command <code>cmd</code>.
</p><p>This computation may fail with
</p><ul><li> <code>PermissionDenied</code>: The process has insufficient privileges to
perform the operation.
</li><li> <code>ResourceExhausted</code>: Insufficient resources are available to
perform the operation.
</li><li> <code>UnsupportedOperation</code>: The implementation does not support
system calls.
</li></ul><p>On Windows, <code><a href="System-Process.html#v:system">system</a></code> passes the command to the Windows command
interpreter (<code>CMD.EXE</code> or <code>COMMAND.COM</code>), hence Unixy shell tricks
will not work.
</p></div></div><div class="top"><p class="src"><a name="v:rawSystem" class="def">rawSystem</a> :: <a href="../base-4.5.1.0/Data-String.html#t:String">String</a> -> [<a href="../base-4.5.1.0/Data-String.html#t:String">String</a>] -> <a href="../base-4.5.1.0/System-IO.html#t:IO">IO</a> <a href="../base-4.5.1.0/System-Exit.html#t:ExitCode">ExitCode</a></p><div class="doc"><p>The computation <code><code><a href="System-Process.html#v:rawSystem">rawSystem</a></code> cmd args</code> runs the operating system command
<code>cmd</code> in such a way that it receives as arguments the <code>args</code> strings
exactly as given, with no funny escaping or shell meta-syntax expansion.
It will therefore behave more portably between operating systems than <code><a href="System-Process.html#v:system">system</a></code>.
</p><p>The return codes and possible failures are the same as for <code><a href="System-Process.html#v:system">system</a></code>.
</p></div></div><div class="top"><p class="src"><a name="v:showCommandForUser" class="def">showCommandForUser</a> :: <a href="../base-4.5.1.0/System-IO.html#t:FilePath">FilePath</a> -> [<a href="../base-4.5.1.0/Data-String.html#t:String">String</a>] -> <a href="../base-4.5.1.0/Data-String.html#t:String">String</a></p><div class="doc"><p>Given a program <code>p</code> and arguments <code>args</code>,
<code>showCommandForUser p args</code> returns a string suitable for pasting
into sh (on POSIX OSs) or cmd.exe (on Windows).
</p></div></div><h1 id="g:3">Process completion
</h1><div class="top"><p class="src"><a name="v:waitForProcess" class="def">waitForProcess</a> :: <a href="System-Process.html#t:ProcessHandle">ProcessHandle</a> -> <a href="../base-4.5.1.0/System-IO.html#t:IO">IO</a> <a href="../base-4.5.1.0/System-Exit.html#t:ExitCode">ExitCode</a></p><div class="doc"><p>Waits for the specified process to terminate, and returns its exit code.
</p><p>GHC Note: in order to call <code>waitForProcess</code> without blocking all the
other threads in the system, you must compile the program with
<code>-threaded</code>.
</p></div></div><div class="top"><p class="src"><a name="v:getProcessExitCode" class="def">getProcessExitCode</a> :: <a href="System-Process.html#t:ProcessHandle">ProcessHandle</a> -> <a href="../base-4.5.1.0/System-IO.html#t:IO">IO</a> (<a href="../base-4.5.1.0/Data-Maybe.html#t:Maybe">Maybe</a> <a href="../base-4.5.1.0/System-Exit.html#t:ExitCode">ExitCode</a>)</p><div class="doc"><p>This is a non-blocking version of <code><a href="System-Process.html#v:waitForProcess">waitForProcess</a></code>. If the process is
still running, <code><a href="../base-4.5.1.0/Data-Maybe.html#v:Nothing">Nothing</a></code> is returned. If the process has exited, then
<code><code><a href="../base-4.5.1.0/Data-Maybe.html#v:Just">Just</a></code> e</code> is returned where <code>e</code> is the exit code of the process.
</p></div></div><div class="top"><p class="src"><a name="v:terminateProcess" class="def">terminateProcess</a> :: <a href="System-Process.html#t:ProcessHandle">ProcessHandle</a> -> <a href="../base-4.5.1.0/System-IO.html#t:IO">IO</a> ()</p><div class="doc"><p>Attempts to terminate the specified process. This function should
not be used under normal circumstances - no guarantees are given regarding
how cleanly the process is terminated. To check whether the process
has indeed terminated, use <code><a href="System-Process.html#v:getProcessExitCode">getProcessExitCode</a></code>.
</p><p>On Unix systems, <code><a href="System-Process.html#v:terminateProcess">terminateProcess</a></code> sends the process the SIGTERM signal.
On Windows systems, the Win32 <code>TerminateProcess</code> function is called, passing
an exit code of 1.
</p><p>Note: on Windows, if the process was a shell command created by
<code><a href="System-Process.html#v:createProcess">createProcess</a></code> with <code><a href="System-Process.html#v:shell">shell</a></code>, or created by <code><a href="System-Process.html#v:runCommand">runCommand</a></code> or
<code><a href="System-Process.html#v:runInteractiveCommand">runInteractiveCommand</a></code>, then <code><a href="System-Process.html#v:terminateProcess">terminateProcess</a></code> will only
terminate the shell, not the command itself. On Unix systems, both
processes are in a process group and will be terminated together.
</p></div></div><div class="top"><p class="src"><a name="v:interruptProcessGroupOf" class="def">interruptProcessGroupOf</a></p><div class="subs arguments"><p class="caption">Arguments</p><table><tr><td class="src">:: <a href="System-Process.html#t:ProcessHandle">ProcessHandle</a></td><td class="doc"><p>A process in the process group
</p></td></tr><tr><td class="src">-> <a href="../base-4.5.1.0/System-IO.html#t:IO">IO</a> ()</td><td class="doc empty"> </td></tr></table></div><div class="doc"><p>Sends an interrupt signal to the process group of the given process.
</p><p>On Unix systems, it sends the group the SIGINT signal.
</p><p>On Windows systems, it generates a CTRL_BREAK_EVENT and will only work for
processes created using <code><a href="System-Process.html#v:createProcess">createProcess</a></code> and setting the <code><a href="System-Process.html#v:create_group">create_group</a></code> flag
</p></div></div></div></div><div id="footer"><p>Produced by <a href="http://www.haskell.org/haddock/">Haddock</a> version 2.11.0</p></div></body></html>
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