| HSH-1.2.4: Library to mix shell scripting with Haskell programs | Contents | Index |
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HSH.Command | Portability | portable | Stability | provisional | Maintainer | John Goerzen <jgoerzen@complete.org> |
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Description |
Copyright (c) 2006-2007 John Goerzen, jgoerzen@complete.org
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Synopsis |
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Documentation |
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class Show a => ShellCommand a where |
A shell command is something we can invoke, pipe to, pipe from,
or pipe in both directions. All commands that can be run as shell
commands must define these methods.
Minimum implementation is fdInvoke.
| | Methods | fdInvoke | :: a | The command
| -> Fd | fd to pass to it as stdin
| -> Fd | fd to pass to it as stdout
| -> [Fd] | Fds to close in the child. Will not harm Fds this child needs for stdin and stdout.
| -> IO () | Action to run post-fork in child (or in main process if it doesn't fork)
| -> IO [InvokeResult] | Returns an action that, when evaluated, waits for the process to finish and returns an exit code.
| Invoke a command.
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| | Instances | |
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data PipeCommand a b |
Constructors | | Instances | |
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(-|-) :: (ShellCommand a, ShellCommand b) => a -> b -> PipeCommand a b |
Pipe the output of the first command into the input of the second.
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class RunResult a where |
Different ways to get data from run.
- IO () runs, throws an exception on error, and sends stdout to stdout
- IO String runs, throws an exception on error, reads stdout into
a buffer, and returns it as a string.
- IO [String] is same as IO String, but returns the results as lines
- IO ProcessStatus runs and returns a ProcessStatus with the exit
information. stdout is sent to stdout. Exceptions are not thrown.
- IO (String, ProcessStatus) is like IO ProcessStatus, but also
includes a description of the last command in the pipe to have
an error (or the last command, if there was no error)
- IO Int returns the exit code from a program directly. If a signal
caused the command to be reaped, returns 128 + SIGNUM.
- IO Bool returns True if the program exited normally (exit code 0,
not stopped by a signal) and False otherwise.
| | Methods | run :: ShellCommand b => b -> a | Runs a command (or pipe of commands), with results presented
in any number of different ways.
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run :: (RunResult a, ShellCommand b) => b -> a |
Runs a command (or pipe of commands), with results presented
in any number of different ways.
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runIO :: ShellCommand a => a -> IO () |
A convenience function. Refers only to the version of run
that returns IO (). This prevents you from having to cast to it
all the time when you do not care about the result of run.
The implementation is simply:
runIO :: (ShellCommand a) => a -> IO ()
runIO = run
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runSL :: ShellCommand a => a -> IO String |
Another convenience function. This returns the first line of the output,
with any trailing newlines or whitespace stripped off. No leading whitespace
is stripped. This function will raise an exception if there is not at least
one line of output. Mnemonic: runSL means "run single line".
This command exists separately from run because there is already a
run instance that returns a String, though that instance returns the
entirety of the output in that String.
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type InvokeResult = (String, IO ProcessStatus) |
Result type for shell commands
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tryEC :: IO a -> IO (Either ProcessStatus a) |
Handle an exception derived from a program exiting abnormally
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catchEC :: IO a -> (ProcessStatus -> IO a) -> IO a |
Catch an exception derived from a program exiting abnormally
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Produced by Haddock version 0.8 |