Safe Haskell	Safe-Inferred
Language	Haskell2010

Pipes.Shell

Contents

Basic combinators
Fancy overloads
Utils

Description

This module contains a few functions to use unix-y shell commands as Pipes.

The output ByteStrings from pipeCmdEnv and friends are not line-wise, but chunk-wise. To get proper lines use the pipes-bytestring and the upcoming pipes-text machinery.

All code examples in this module assume following qualified imports: Pipes.Prelude as P, Pipes.ByteString as PBS, Data.ByteString.Char8 as BSC

Synopsis

Basic combinators

pipeCmdEnv :: MonadSafe m => Maybe [(String, String)] -> String -> Pipe (Maybe ByteString) (Either ByteString ByteString) m () Source

This is the workhorse of this package.

It provides the direct interface from a shell command string to a proper Pipe.

>>> runShell $ yield (BSC.pack "aaa") >?> pipeCmdEnv Nothing "tr 'a' 'A'" >-> PBS.stdout
AAA

pipeCmd :: MonadSafe m => String -> Pipe (Maybe ByteString) (Either ByteString ByteString) m () Source

Like pipeCmdEnv but doesn't set enviorment varaibles

pipeCmd' :: MonadSafe m => String -> Pipe (Maybe ByteString) ByteString m () Source

Like pipeCmd but ignores stderr

producerCmdEnv :: MonadSafe m => Maybe [(String, String)] -> String -> Producer (Either ByteString ByteString) m () Source

Like pipeCmdEnv but closes the input end immediately.

Useful for command line tools like ls

producerCmd :: MonadSafe m => String -> Producer (Either ByteString ByteString) m () Source

Like producerCmdEnv but doesn't set enviorment varaibles

producerCmd' :: MonadSafe m => String -> Producer ByteString m () Source

Like producerCmd but ignores stderr

consumerCmdEnv :: MonadSafe m => Maybe [(String, String)] -> String -> Consumer (Maybe ByteString) m () Source

Like pipeCmd but closes the output end immediately.

Useful for command line tools like cat > test.file

consumerCmd :: MonadSafe m => String -> Consumer (Maybe ByteString) m () Source

Like consumerCmdEnv but doesn't set enviorment varaibles

Fancy overloads

class Cmd cmd where Source

An ad-hoc typeclass to get the varadic arguments and DWIM behavoir of cmdEnv

Minimal complete definition

cmdEnv

Methods

cmdEnv :: Maybe [(String, String)] -> String -> cmd Source

Like pipeCmdEnv, producerCmdEnv or consumerCmdEnv depending on the context. It also supports varadic arguments.

Examples:

As Pipe:

>>> runShell $ yield (BSC.pack "aaa") >?> cmd "tr 'a' 'A'" >-> ignoreErr >-> PBS.stdout
AAA

As Producer:

>>> runShell $ cmd "ls" >-> ignoreErr >-> PBS.stdout
<output from ls on the current directory>

As Consumer:

>>> runShell $ yield (BSC.pack "aaa") >?> cmd "cat > test.file"
<a new file with "aaa" in it>

cmd :: Cmd cmd => String -> cmd Source

Like cmdEnv but doesn't set enviorment varaibles

Instances

Cmd cmd => Cmd (String -> cmd)
MonadSafe m => Cmd (Producer (Either ByteString ByteString) m ())
MonadSafe m => Cmd (Consumer (Maybe ByteString) m ())
MonadSafe m => Cmd (Pipe (Maybe ByteString) (Either ByteString ByteString) m ())

class Cmd' cmd where Source

An ad-hoc typeclass to get the varadic arguments and DWIM behavoir of cmd'. This class is seperate from Cmd to make the return types work out.

Methods

cmd' :: String -> cmd Source

Like cmd but uses ignoreErr automatically. So it's like pipeCmd', producerCmd' or consumerCmd depending on context. It supports the same style of varadic arguments as cmd

Instances

Cmd' cmd => Cmd' (String -> cmd)
MonadSafe m => Cmd' (Producer ByteString m ())
MonadSafe m => Cmd' (Consumer (Maybe ByteString) m ())
MonadSafe m => Cmd' (Pipe (Maybe ByteString) ByteString m ())

Utils

(>?>) :: Monad m => Proxy a' a () b m r -> Proxy () (Maybe b) c' c m r -> Proxy a' a c' c m r infixl 7 Source

Like >-> but marks the end of the left pipe with markEnd. It's needed because pipeCmdEnv has to know when the upstream Pipe finishes.

The basic rule is:

 Replace every >-> with >?> when it's in front of
   pipeCmdEnv or similar.

markEnd :: Monad m => Proxy a' a b' b m r -> Proxy a' a b' (Maybe b) m r Source

Mark the end of a pipe. It wraps all values in a Just and yields *one* Nothing after the upstream pipe finished.

ignoreErr :: Monad m => Pipe (Either ByteString ByteString) ByteString m () Source

Ignore stderr from a pipeCmd

ignoreOut :: Monad m => Pipe (Either ByteString ByteString) ByteString m () Source

Ignore stdout from a pipeCmd

runShell :: Effect (SafeT IO) r -> IO r Source

A simple run function for Pipes that live in SafeT IO