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| System.Posix.Process | | Portability | non-portable (requires POSIX) | | Stability | provisional | | Maintainer | libraries@haskell.org |
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| Description |
| POSIX process support. See also the System.Cmd and System.Process
modules.
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| Synopsis |
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| Processes
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| Forking and executing
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| forkProcess :: IO () -> IO ProcessID |
forkProcess corresponds to the POSIX fork system call.
The IO action passed as an argument is executed in the child process; no other
threads will be copied to the child process.
On success, forkProcess returns the child's ProcessID to the parent process;
in case of an error, an exception is thrown.
forkProcess comes with a giant warning: since any other running
threads are not copied into the child process, it's easy to go wrong:
e.g. by accessing some shared resource that was held by another thread
in the parent. Another example is the I/O manager thread: since the
I/O manager isn't running in the child, attempting to do any
Handle-based I/O will deadlock.
Using forkProcess in order to do executeFile is likely to work.
Anything else: you're on your own.
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| executeFile |
| :: FilePath | Command
| | -> Bool | Search PATH?
| | -> [String] | Arguments
| | -> Maybe [(String, String)] | Environment
| | -> IO () | | | executeFile cmd args env calls one of the
execv* family, depending on whether or not the current
PATH is to be searched for the command, and whether or not an
environment is provided to supersede the process's current
environment. The basename (leading directory names suppressed) of
the command is passed to execv* as arg[0];
the argument list passed to executeFile therefore
begins with arg[1].
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| Exiting
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| exitImmediately :: ExitCode -> IO () |
| exitImmediately status calls _exit to terminate the process
with the indicated exit status.
The operation never returns.
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| Process environment
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| getProcessID :: IO ProcessID |
| getProcessID calls getpid to obtain the ProcessID for
the current process.
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| getParentProcessID :: IO ProcessID |
| getProcessID calls getppid to obtain the ProcessID for
the parent of the current process.
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| getProcessGroupID :: IO ProcessGroupID |
| getProcessGroupID calls getpgrp to obtain the
ProcessGroupID for the current process.
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| Process groups
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| createProcessGroup :: ProcessID -> IO ProcessGroupID |
| createProcessGroup pid calls setpgid to make
process pid a new process group leader.
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| joinProcessGroup :: ProcessGroupID -> IO () |
| joinProcessGroup pgid calls setpgid to set the
ProcessGroupID of the current process to pgid.
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| setProcessGroupID :: ProcessID -> ProcessGroupID -> IO () |
| setProcessGroupID pid pgid calls setpgid to set the
ProcessGroupID for process pid to pgid.
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| Sessions
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| createSession :: IO ProcessGroupID |
| createSession calls setsid to create a new session
with the current process as session leader.
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| Process times
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| data ProcessTimes |
| Constructors | | ProcessTimes | | | elapsedTime :: ClockTick | | | userTime :: ClockTick | | | systemTime :: ClockTick | | | childUserTime :: ClockTick | | | childSystemTime :: ClockTick | |
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| getProcessTimes :: IO ProcessTimes |
| getProcessTimes calls times to obtain time-accounting
information for the current process and its children.
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| Scheduling priority
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| nice :: Int -> IO () |
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| getProcessPriority :: ProcessID -> IO Int |
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| getProcessGroupPriority :: ProcessGroupID -> IO Int |
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| getUserPriority :: UserID -> IO Int |
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| setProcessPriority :: ProcessID -> Int -> IO () |
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| setProcessGroupPriority :: ProcessGroupID -> Int -> IO () |
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| setUserPriority :: UserID -> Int -> IO () |
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| Process status
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| data ProcessStatus |
| Constructors | |  Instances | |
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| getProcessStatus :: Bool -> Bool -> ProcessID -> IO (Maybe ProcessStatus) |
| getProcessStatus blk stopped pid calls waitpid, returning
Just tc, the ProcessStatus for process pid if it is
available, Nothing otherwise. If blk is False, then
WNOHANG is set in the options for waitpid, otherwise not.
If stopped is True, then WUNTRACED is set in the
options for waitpid, otherwise not.
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| getAnyProcessStatus :: Bool -> Bool -> IO (Maybe (ProcessID, ProcessStatus)) |
| getAnyProcessStatus blk stopped calls waitpid, returning
Just (pid, tc), the ProcessID and ProcessStatus for any
child process if one is available, Nothing otherwise. If
blk is False, then WNOHANG is set in the options for
waitpid, otherwise not. If stopped is True, then
WUNTRACED is set in the options for waitpid, otherwise not.
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| getGroupProcessStatus :: Bool -> Bool -> ProcessGroupID -> IO (Maybe (ProcessID, ProcessStatus)) |
| getGroupProcessStatus blk stopped pgid calls waitpid,
returning Just (pid, tc), the ProcessID and
ProcessStatus for any process in group pgid if one is
available, Nothing otherwise. If blk is False, then
WNOHANG is set in the options for waitpid, otherwise not.
If stopped is True, then WUNTRACED is set in the
options for waitpid, otherwise not.
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| Produced by Haddock version 0.8 |
