eXept Software AG Logo

Smalltalk/X Webserver

Documentation of class 'OSProcess':

Home

Documentation
www.exept.de
Everywhere
for:
[back]

Class: OSProcess


Inheritance:

   Object
   |
   +--OSProcess
      |
      +--OSProcess::RemoteOSProcess

Package:
stx:libbasic
Category:
System-Support
Version:
rev: 1.41 date: 2018/05/24 16:07:14
user: stefan
file: OSProcess.st directory: libbasic
module: stx stc-classLibrary: libbasic
Author:
Stefan Vogel (stefan@zwerg)

Description:


Instances of OSProcess represent operating system processes that can be executed.
(as opposed to Smalltalk processes).
Both local and remote processes are suported.

commandString:
 If command is a String, the commandString is passed to a shell for execution
 - see the description of 'sh -c' in your UNIX manual ('cmd.exe' in your Windows manual).
 Regular input/output redirection and pipes etc. are supported as supported by
 the underlying OS's command interpreter (i.e. some limits apply to MSDOS)

 With an empty command, the shell will read commands from the passed input stream.

 If command is an Array, the first element is the command to be executed,
 and the other elements are the arguments to the command. 
 No shell is invoked in this case. Any redirection or piping can then be done
 by Smalltalk code (including piping through smalltalk streams & filters).


[instance variables:]
    pid         SmallInteger    the process id
    command     String          the command line of the running command.

[class variables:]


Related information:

    Process

Class protocol:

class initialization
o  initialize
Backward compatibility: Win32Process is an alias for OSProcess

instance creation
o  command: aCommandString
return an initialized instance to execute aCommandString
in the current directory (for a local process)

o  command: aCommandString directory: aStringOrFilename
return an initialized instance to execute aCommandString
in a given directory (for a local process)

o  commandStringForProgramName: executableFile arguments: arrayOfStrings

o  new
return an initialized instance for a local process

o  onHost: aHost
return an initialized instance for a remote process running on another host
usage example(s):
     OSProcess onHost:'localhost'
     OSProcess onHost:'exeptn'

     (OSProcess new) command:'ls'
     (OSProcess onHost:'exeptn') command:'ls'

o  possiblyQuoted: aString
should we quote or escape?
usage example(s):
     self possiblyQuoted:'foo bar' 
     self possiblyQuoted:'foo\bar'

o  programName: executableFile arguments: arrayOfStrings initialEnvironment: stringDictionary
similar to command:, but with separate command and arguments

queries
o  defaultShellPath


Instance protocol:

accessing
o  auxStream

o  auxStream: something
set an auxiliary input stream that will be available to the command as
file descriptor 3

o  command
the OS (shell-) command

o  command: aStringOrArray
set the command to be executed.

If aStringOrArray is a String, the commandString is passed to a shell for execution
- see the description of 'sh -c' in your UNIX manual ('cmd.exe' in your Windows manual).
With an empty command, the shell will read commands from the passed input stream.

If aCommandString is an Array, the first element is the command to be executed,
and the other elements are the arguments to the command.
No shell is invoked in this case.

o  command: commandStringArg directory: stringOrFilenameArg
set the command to be executed and directory, where to execute.
If aStringOrArray is a String, the commandString is passed to a shell for execution
- see the description of 'sh -c' in your UNIX manual ('cmd.exe' in your Windows manual).
If aCommandString is an Array, the first element is the command to be executed,
and the other elements are the arguments to the command. No shell is invoked in this case.

o  command: commandArg environment: environmentArg directory: directoryArg inStream: inStreamArg outStream: outStreamArg errorStream: errorStreamArg auxStream: auxStreamArg showWindow: showWindowArg lineWise: lineWiseArg
set the command to be executed & directory, where to execute.
and input/output streams.
See comments in individual setters for more info

o  directory
the directory where executed

o  directory: aStringOrFilename
set the directory that will be set as the current directory of the command to be executed

o  environment
the shell environment

o  environment: aDictionary
set the environment variables of the command to be executed

o  errorStream

o  errorStream: aStream
set the stream where the stderr output of the command is directed to

o  exitStatus
answer the exit status of the command or nil, if the command has not yet been finished

o  exitStatus: something
set the value of the instance variable 'exitStatus' (automatically generated)

o  finishSema
wait on this semaphore if you want to wait until the OS process has finished.
There may be multiple waiters, so it is a good idea to do a #waitUncounted

o  inStream

o  inStream: aStream
set the stream where the stdin input of the command is read from

o  lineWise

o  lineWise: aBoolean
When setting to true, read linewise from the command's output and error.
This is a bit slower than lineWise = false.

You may use it also when streaming to e.g. Transcript

o  newPgrp

o  newPgrp: aBoolean
if aBoolean is true, a new process group will be created for the command and its subprocesses

o  outStream
the stream where the stdout output of the command is directed to

o  outStream: aStream
set the stream where the stdout output of the command is directed to

o  pid
answer the pid of the process the command is running in or nil, if the command has not yet been started.

o  showWindow

o  showWindow: aBooleanOrNil
This parameter is ignored on Unix systems.

You can control (have to - sigh) if a window should be shown for the command or not.
This is the OS's H_SHOWWINDOW argument.
If you pass nil as showWindow-argument, the OS's default is used for the particular
command, which is correct most of the time: i.e. a notepad will open its window, other (non-UI)
executables will not.
However, some command-line executables show a window, even if they should not.
(and also, there seems to be an inconsistency between windows7 and newer windows: in newer,
a shell command opens a cmd-window, whereas in windows7 it did not)
In this case, pass an explicit false argument to suppress it.

o  terminateActionBlock
the (user provided) callback block,
that will be executed when the command has finished or was terminated.
If non-nil, it will be called with optional argument:status and:self, the OSProcess.

o  terminateActionBlock: aBlock
set the callback block,
that will be called when the command has finished or was terminated.
If non-nil, it will be called with optional argument:status and:self, the OSProcess.
WARNING:
if the active-process calling #startProcess is already dead (i.e. terminated),
this callback will be called by the scheduler;
otherwise, the calling process will be interrupted to perform this callback.
Therefore: do not open any GUI or other blocking actions in it.

initialization
o  initialize
Invoked when a new instance is created.

inspecting
o  inspectorExtraMenuOperations
( an extension from the stx:libtool package )
extra operation-menu entries to be shown in an inspector.
Answers a collection of pairs contining aString and action aBlock.
aString is the label of the menu item.
aBlock is evaluated when the menu item is selected.
To be redefined in objects which think that it makes sense to offer
often used operations in an inspector.
See SerialPort as an example.

printing
o  printOn: aStream

private
o  setupShufflerForInput: aStream
if aStream is an internal Stream, set up a pipe for the command input.
Start a process that shuffles the data from the internal stream into the pipe
(and into the command's input).

o  setupShufflerForOutput: aStream
if aStream is an internal Stream, set up a pipe for the command output.
Start a process that shuffles the data fron the pipe into the internal stream.

o  startCommand
the 'real' command to be executed.
Redefined for remote processes (eg. to construct a remote command string).
Command may be both an Array or a String

queries
o  finishedWithSuccess

o  isAlive
answer true if the process is still alive

o  isDead
answer true if the process is no longer alive

starting
o  execute
execute the command.
Wait until it is finished.
Abort the execution if I am interrupted.
Answer true if it terminated successfully,
false if it could not be started or terminated with error.

o  startProcess
Start the command asynchronously (i.e. don't wait until is has finished).
If there are non-external streams, setup transfer (shuffler) processes
to transfer data from a pipe to the internal stream.

Answer true if the command could started succesfully, false if not.

NOTE: under normal circumstances, even if the command cannot be found,
the exit fom the command interpreter/shell is done some time later
So you have to check later or set #terminateActionBlock: and check there.

terminating
o  kill
kill the process - the process does not get the chance to clean up

o  killGroup
kill the processGroup - the processes do not get the chance to clean up

o  terminate
terminate the process gracefully

o  terminateGroup
terminate the process group.
Under Windows, this is the same as terminateWithAllChildren,
under unix, this terminates a subset of all children

waiting
o  waitUntilFinished
wait with a veryy long timeout,
in order that ProcessorScheduler>>#checkForEndOfDispatch recogizes
this waiting process as user process which is still alive.
The timout is meant to never occur!

o  waitUntilFinishedWithTimeout: timeout
timed out


Private classes:

    RemoteOSProcess

Examples:


send command's output to the Transcript:
  OSProcess new 
      terminateActionBlock:[:status | Transcript showCR:status. Transcript showCR:status isError];
      command:'lsxxxx -l';
      outStream:Transcript;
      lineWise:true;
      startProcess.
send command's output to my stdout (see console):
  OSProcess new 
      command:'ls -l';
      outStream:Stdout;
      execute.
send command's output to a Smalltalk stream:
  |outStream|

  outStream := '' writeStream.

  OSProcess new 
      command:'ls -l';
      outStream:outStream;
      execute.

  outStream contents inspect.
feed it from a smalltalk stream, get command's output into a Smalltalk stream:
  |inStream outStream|

  inStream := 'hello world' readStream.
  outStream := '' writeStream.

  OSProcess new 
      command:'tr ''a-z'' ''A-Z''';
      inStream:inStream;
      outStream:outStream;
      execute.

  outStream contents inspect.
again, send output to a Smalltalk stream; watch the stream getting filled after 10 seconds:
  |outStream|

  outStream := '' writeStream.

  OSProcess new 
      command:'ls -l; sleep 10; echo =================================; echo hallo after 10s; echo >&2 +++++++++++++++++++++; cat >&2';
      outStream:outStream;
      errorStream:outStream;
      startProcess.

  outStream inspect
separate stdout and stderr:
  |outStream errStream|

  outStream := '' writeStream.
  errStream := '' writeStream.

  OSProcess new 
      command:'ls -l && ls >&2';
      outStream:outStream;
      errorStream:errStream;
      startProcess.

  outStream inspect.
  errStream inspect.
Execute commands in shell/cmd.exe and read them from stdin:
  |outStream|

  outStream := '' writeStream.

  OSProcess new 
      command:'';
      inStream:'ls -l' readStream;
      outStream:outStream;
      lineWise:true;
      execute.

  outStream contents inspect
Execute on a remote host (you must have the appropriate ssh setup):
  |outStream|

  outStream := '' writeStream.

  (OSProcess onHost:'exeptn') 
      command:'ls -l';
      outStream:outStream;
      lineWise:true;
      execute.

  outStream contents inspect


ST/X 7.1.0.0; WebServer 1.663 at exept.de:8081; Mon, 23 Jul 2018 11:44:21 GMT