-- Hoogle documentation, generated by Haddock
-- See Hoogle, http://www.haskell.org/hoogle/

-- | Library to mix shell scripting with Haskell programs
--   
--   HSH is designed to let you mix and match shell expressions with
--   Haskell programs. With HSH, it is possible to easily run shell
--   commands, capture their output or provide their input, and pipe them
--   to and from other shell commands and arbitrary Haskell functions at
--   will. Category: System
@package HSH
@version 2.1.3

-- | Copyright (c) 2006-2009 John Goerzen, jgoerzen@complete.org
module HSH.Channel

-- | The main type for communicating between commands. All are expected to
--   be lazy.
data Channel
ChanString :: String -> Channel
ChanBSL :: ByteString -> Channel
ChanHandle :: Handle -> Channel
chanAsString :: Channel -> IO String
chanAsBSL :: Channel -> IO ByteString
chanAsBS :: Channel -> IO ByteString

-- | Writes the Channel to the given Handle. If the first parameter is
--   True, do this in a separate thread and close the handle afterwards.
chanToHandle :: Bool -> Channel -> Handle -> IO ()
class Channelizable a
toChannel :: Channelizable a => a -> Channel
instance HSH.Channel.Channelizable GHC.Base.String
instance HSH.Channel.Channelizable Data.ByteString.Lazy.Internal.ByteString
instance HSH.Channel.Channelizable GHC.IO.Handle.Types.Handle
instance HSH.Channel.Channelizable Data.ByteString.Internal.ByteString

-- | Copyright (c) 2006-2009 John Goerzen, jgoerzen@complete.org
module HSH.Command

-- | Type for the environment.
type Environment = Maybe [(String, String)]

-- | 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.
--   
--   Some pre-defined instances include:
--   
--   
--   
- A simple bare string, which is passed to the shell for execution.
--   The shell will then typically expand wildcards, parse parameters,
--   etc.
--   
- A (String, [String]) tuple. The first item in the tuple
--   gives the name of a program to run, and the second gives its
--   arguments. The shell is never involved. This is ideal for passing
--   filenames, since there is no security risk involving special shell
--   characters.
--   
- A Handle -> Handle -> IO () function, which reads
--   from the first handle and write to the second.
--   
- Various functions. These functions will accept input representing
--   its standard input and output will go to standard output.
--   
--   
--   Some pre-defined instance functions include:
--   
--   
--   
- (String -> String), (String -> IO String),
--   plus the same definitions for ByteStrings.
--   
- ([String] -> [String]), ([String] -> IO
--   [String]), where each String in the list represents a
--   single line
--   
- (() -> String), (() -> IO String), for
--   commands that explicitly read no input. Useful with closures. Useful
--   when you want to avoid reading stdin because something else already
--   is. These have the unit as part of the function because otherwise we
--   would have conflicts with things such as bare Strings, which represent
--   a command name.
--   
class (Show a) => ShellCommand a

-- | Invoke a command.
fdInvoke :: ShellCommand a => a -> Environment -> Channel -> IO (Channel, [InvokeResult])
data PipeCommand a b
PipeCommand :: a -> b -> PipeCommand a b

-- | Pipe the output of the first command into the input of the second.
(-|-) :: (ShellCommand a, ShellCommand b) => a -> b -> PipeCommand a b

-- | 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. Note: This output is not
--   lazy.
--   
- IO [String] is same as IO String, but returns the results as
--   lines. Note: this output is not lazy.
--   
- IO ExitCode runs and returns an ExitCode with the exit
--   information. stdout is sent to stdout. Exceptions are not thrown.
--   
- IO (String, ExitCode) is like IO ExitCode, 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 ByteString and are similar to their String counterparts.
--   
- IO (String, IO (String, ExitCode)) returns a String read lazily
--   and an IO action that, when evaluated, finishes up the process and
--   results in its exit status. This command returns immediately.
--   
- IO (IO (String, ExitCode)) sends stdout to stdout but returns
--   immediately. It forks off the child but does not wait for it to
--   finish. You can use checkResults to wait for the finish.
--   
- 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.
--   
--   
--   To address insufficient laziness, you can process anything that needs
--   to be processed lazily within the pipeline itself.
class RunResult a

-- | Runs a command (or pipe of commands), with results presented in any
--   number of different ways.
run :: (RunResult a, ShellCommand b) => b -> a

-- | 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
--   
runIO :: ShellCommand a => a -> IO ()

-- | 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.
runSL :: ShellCommand a => a -> IO String

-- | Result type for shell commands. The String is the text description of
--   the command, not its output.
type InvokeResult = (String, IO ExitCode)

-- | Evaluates result codes and raises an error for any bad ones it finds.
checkResults :: (String, ExitCode) -> IO ()

-- | Handle an exception derived from a program exiting abnormally
tryEC :: IO a -> IO (Either ExitCode a)

-- | Catch an exception derived from a program exiting abnormally
catchEC :: IO a -> (ExitCode -> IO a) -> IO a

-- | Sets an environment variable, replacing an existing one if it exists.
--   
--   Here's a sample ghci session to illustrate. First, let's see the
--   defaults for some variables:
--   
--   
--   Prelude HSH> runIO $ "echo $TERM, $LANG"
--   xterm, en_US.UTF-8
--   
--   
--   Now, let's set one:
--   
--   
--   Prelude HSH> runIO $ setenv [("TERM", "foo")] $ "echo $TERM, $LANG"
--   foo, en_US.UTF-8
--   
--   
--   Or two:
--   
--   
--   Prelude HSH> runIO $ setenv [("TERM", "foo")] $ setenv [("LANG", "de_DE.UTF-8")] $ "echo $TERM, $LANG"
--   foo, de_DE.UTF-8
--   
--   
--   We could also do it easier, like this:
--   
--   
--   Prelude HSH> runIO $ setenv [("TERM", "foo"), ("LANG", "de_DE.UTF-8")] $ "echo $TERM, $LANG"
--   foo, de_DE.UTF-8
--   
--   
--   It can be combined with unsetenv:
--   
--   
--   Prelude HSH> runIO $ setenv [("TERM", "foo")] $ unsetenv ["LANG"] $ "echo $TERM, $LANG"
--   foo,
--   
--   
--   And used with pipes:
--   
--   
--   Prelude HSH> runIO $ setenv [("TERM", "foo")] $ "echo $TERM, $LANG" -|- "tr a-z A-Z"
--   FOO, EN_US.UTF-8
--   
--   
--   See also unsetenv.
setenv :: ShellCommand cmd => [(String, String)] -> cmd -> EnvironCommand cmd

-- | Removes an environment variable if it exists; does nothing otherwise.
--   
--   See also setenv, which has a more extensive example.
unsetenv :: ShellCommand cmd => [String] -> cmd -> EnvironCommand cmd
instance GHC.Show.Show (HSH.Command.PipeCommand a b)
instance GHC.Show.Show (HSH.Command.EnvironCommand a)
instance HSH.Command.ShellCommand a => HSH.Command.ShellCommand (HSH.Command.EnvironCommand a)
instance GHC.Show.Show HSH.Command.EnvironFilter
instance HSH.Command.RunResult (GHC.Types.IO ())
instance HSH.Command.RunResult (GHC.Types.IO (GHC.Base.String, GHC.IO.Exception.ExitCode))
instance HSH.Command.RunResult (GHC.Types.IO GHC.IO.Exception.ExitCode)
instance HSH.Command.RunResult (GHC.Types.IO GHC.Types.Int)
instance HSH.Command.RunResult (GHC.Types.IO GHC.Types.Bool)
instance HSH.Command.RunResult (GHC.Types.IO [GHC.Base.String])
instance HSH.Command.RunResult (GHC.Types.IO GHC.Base.String)
instance HSH.Command.RunResult (GHC.Types.IO Data.ByteString.Lazy.Internal.ByteString)
instance HSH.Command.RunResult (GHC.Types.IO Data.ByteString.Internal.ByteString)
instance HSH.Command.RunResult (GHC.Types.IO (GHC.Base.String, GHC.Types.IO (GHC.Base.String, GHC.IO.Exception.ExitCode)))
instance HSH.Command.RunResult (GHC.Types.IO (Data.ByteString.Lazy.Internal.ByteString, GHC.Types.IO (GHC.Base.String, GHC.IO.Exception.ExitCode)))
instance HSH.Command.RunResult (GHC.Types.IO (Data.ByteString.Internal.ByteString, GHC.Types.IO (GHC.Base.String, GHC.IO.Exception.ExitCode)))
instance HSH.Command.RunResult (GHC.Types.IO (GHC.Types.IO (GHC.Base.String, GHC.IO.Exception.ExitCode)))
instance (HSH.Command.ShellCommand a, HSH.Command.ShellCommand b) => HSH.Command.ShellCommand (HSH.Command.PipeCommand a b)
instance HSH.Command.ShellCommand (GHC.Base.String -> GHC.Types.IO GHC.Base.String)
instance HSH.Command.ShellCommand (() -> GHC.Types.IO GHC.Base.String)
instance HSH.Command.ShellCommand (Data.ByteString.Lazy.Internal.ByteString -> GHC.Types.IO Data.ByteString.Lazy.Internal.ByteString)
instance HSH.Command.ShellCommand (() -> GHC.Types.IO Data.ByteString.Lazy.Internal.ByteString)
instance HSH.Command.ShellCommand (Data.ByteString.Internal.ByteString -> GHC.Types.IO Data.ByteString.Internal.ByteString)
instance HSH.Command.ShellCommand (() -> GHC.Types.IO Data.ByteString.Internal.ByteString)
instance HSH.Command.ShellCommand (GHC.Base.String -> GHC.Base.String)
instance HSH.Command.ShellCommand (() -> GHC.Base.String)
instance HSH.Command.ShellCommand (Data.ByteString.Lazy.Internal.ByteString -> Data.ByteString.Lazy.Internal.ByteString)
instance HSH.Command.ShellCommand (() -> Data.ByteString.Lazy.Internal.ByteString)
instance HSH.Command.ShellCommand (Data.ByteString.Internal.ByteString -> Data.ByteString.Internal.ByteString)
instance HSH.Command.ShellCommand (() -> Data.ByteString.Internal.ByteString)
instance HSH.Command.ShellCommand (HSH.Channel.Channel -> GHC.Types.IO HSH.Channel.Channel)
instance HSH.Command.ShellCommand ([GHC.Base.String] -> [GHC.Base.String])
instance HSH.Command.ShellCommand (() -> [GHC.Base.String])
instance HSH.Command.ShellCommand ([GHC.Base.String] -> GHC.Types.IO [GHC.Base.String])
instance HSH.Command.ShellCommand (() -> GHC.Types.IO [GHC.Base.String])
instance HSH.Command.ShellCommand (GHC.Base.String, [GHC.Base.String])
instance HSH.Command.ShellCommand GHC.Base.String
instance GHC.Show.Show (GHC.IO.Handle.Types.Handle -> GHC.IO.Handle.Types.Handle -> GHC.Types.IO ())
instance GHC.Show.Show (HSH.Channel.Channel -> GHC.Types.IO HSH.Channel.Channel)
instance GHC.Show.Show (GHC.Base.String -> GHC.Base.String)
instance GHC.Show.Show (() -> GHC.Base.String)
instance GHC.Show.Show (GHC.Base.String -> GHC.Types.IO GHC.Base.String)
instance GHC.Show.Show (() -> GHC.Types.IO GHC.Base.String)
instance GHC.Show.Show (Data.ByteString.Lazy.Internal.ByteString -> Data.ByteString.Lazy.Internal.ByteString)
instance GHC.Show.Show (() -> Data.ByteString.Lazy.Internal.ByteString)
instance GHC.Show.Show (Data.ByteString.Lazy.Internal.ByteString -> GHC.Types.IO Data.ByteString.Lazy.Internal.ByteString)
instance GHC.Show.Show (() -> GHC.Types.IO Data.ByteString.Lazy.Internal.ByteString)
instance GHC.Show.Show (Data.ByteString.Internal.ByteString -> Data.ByteString.Internal.ByteString)
instance GHC.Show.Show (() -> Data.ByteString.Internal.ByteString)
instance GHC.Show.Show (Data.ByteString.Internal.ByteString -> GHC.Types.IO Data.ByteString.Internal.ByteString)
instance GHC.Show.Show (() -> GHC.Types.IO Data.ByteString.Internal.ByteString)
instance GHC.Show.Show ([GHC.Base.String] -> [GHC.Base.String])
instance GHC.Show.Show (() -> [GHC.Base.String])
instance GHC.Show.Show ([GHC.Base.String] -> GHC.Types.IO [GHC.Base.String])
instance GHC.Show.Show (() -> GHC.Types.IO [GHC.Base.String])

-- | Copyright (c) 2006-2009 John Goerzen, jgoerzen@complete.org
--   
--   This module provides shell-like commands. Most, but not all, are
--   designed to be used directly as part of a HSH pipeline. All may be
--   used outside HSH entirely as well.
module HSH.ShellEquivs

-- | Return the absolute path of the arg. Raises an error if the
--   computation is impossible. This is a thin wrapper around
--   System.Path.absNormPath. Unix/Linux users note:
--   System.Path.absNormPath is known to produce odd results when a tilde
--   expansion is requested; you might prefer glob to this function
--   if you know your input is free of wildcards. See
--   https:/github.comjgoerzenhshissues/7 for details.
abspath :: FilePath -> IO FilePath

-- | Like catTo, but appends to the file.
appendTo :: FilePath -> String -> IO String

-- | The filename part of a path
basename :: FilePath -> FilePath

-- | Changes the current working directory to the given path, executes the
--   given I/O action, then changes back to the original directory, even if
--   the I/O action raised an exception.
--   
--   This is an alias for the MissingH function System.Path.bracketCWD.
bracketCD :: FilePath -> IO a -> IO a

-- | Load the specified files and display them, one at a time.
--   
--   The special file - means to display the input. If it is not
--   given, no input is processed at all.
--   
--   - may be given a maximum of one time.
--   
--   See also catBytes .
catFrom :: [FilePath] -> Channel -> IO Channel

-- | Copy data from input to output, optionally with a fixed maximum size,
--   in bytes. Processes data using ByteStrings internally, so be aware of
--   any possible UTF-8 conversions.
--   
--   You may wish to use hSetBuffering h (BlockBuffering Nothing)
--   prior to calling this function for optimal performance.
--   
--   See also catFrom, catBytesFrom
catBytes :: Maybe Integer -> Channel -> IO Channel

-- | Generic version of catBytes; reads data from specified Channel,
--   and ignores stdin.
catBytesFrom :: Channel -> Maybe Integer -> Channel -> IO Channel

-- | Takes input, writes it to the specified file, and does not pass it on.
--   The return value is the empty string. See also catToBS,
--   catToFIFO
catTo :: FilePath -> Channel -> IO Channel

-- | Like catTo, but opens the destination in ReadWriteMode instead
--   of ReadOnlyMode. Due to an oddity of the Haskell IO system, this is
--   required when writing to a named pipe (FIFO) even if you will never
--   read from it.
--   
--   This call will BLOCK all threads on open until a reader connects.
--   
--   This is provided in addition to catTo because you may want to
--   cat to something that you do not have permission to read from.
--   
--   This function is only available on POSIX platforms.
--   
--   See also catTo
catToFIFO :: FilePath -> Channel -> IO Channel

-- | An alias for System.Directory.setCurrentDirectory.
--   
--   Want to change to a user's home directory? Try this:
--   
--   
--   glob "~jgoerzen" >>= cd . head
--   
--   
--   See also bracketCD.
cd :: FilePath -> IO ()

-- | Split a list by a given character and select the nth list.
--   
--   
--   cut ' ' 2 "foo bar baz quux" -> "bar"
--   
cut :: Integer -> Char -> String -> String

-- | Split a list by a given character and select ranges of the resultant
--   lists.
--   
--   
--   cutR [2..4] ' ' "foo bar baz quux foobar" -> "baz quux foobar"
--   cutR [1..1000] ' ' "foo bar baz quux foobar" -> "bar baz quux foobar"
--   cutR [-1000..1000] ' ' "foo bar baz quux foobar" -> "foo bar baz quux foobar"
--   
--   
--   Note that too large and too small indices are essentially ignored.
cutR :: [Integer] -> Char -> String -> String

-- | The directory part of a path
dirname :: FilePath -> FilePath

-- | Read all input and produce no output. Discards input completely.
discard :: Channel -> IO Channel

-- | Takes a string and sends it on as standard output.
--   
--   The input to this function is never read.
--   
--   You can pass this thing a String, a ByteString, or even a Handle.
--   
--   See also echoBS.
echo :: Channelizable a => a -> Channel -> IO Channel

-- | Exits with the specified error code. 0 indicates no error.
exit :: Int -> IO a

-- | Takes a pattern. Returns a list of names that match that pattern.
--   Handles:
--   
--   
--   ~username at beginning of file to expand to user's home dir
--   ? matches exactly one character
--   * matches zero or more characters
--   [list] matches any character in list
--   [!list] matches any character not in list
--   
--   
--   The result of a tilde expansion on a nonexistant username is to do no
--   tilde expansion.
--   
--   The tilde with no username equates to the current user.
--   
--   Non-tilde expansion is done by the MissingH module System.Path.Glob.
glob :: FilePath -> IO [FilePath]

-- | Search for the string in the lines. Return those that match. Same as:
--   
--   
--   grep needle = filter (isInfixOf needle)
--   
grep :: String -> [String] -> [String]

-- | Search for the string in the lines. Return those that do NOT match.
grepV :: String -> [String] -> [String]

-- | Search for the regexp in the lines. Return those that match.
egrep :: String -> [String] -> [String]

-- | Search for the regexp in the lines. Return those that do NOT match.
egrepV :: String -> [String] -> [String]

-- | Join lines of a file
joinLines :: [String] -> [String]

-- | Convert a string to all lower case
lower :: String -> String

-- | Convert a string to all upper case
upper :: String -> String

-- | Creates the given directory. A value of 0o755 for mode would be
--   typical.
--   
--   An alias for System.Posix.Directory.createDirectory.
--   
--   The second argument will be ignored on non-POSIX systems.
mkdir :: FilePath -> FileMode -> IO ()

-- | Number each line of a file
numberLines :: [String] -> [String]

-- | An alias for System.Directory.getCurrentDirectory.
pwd :: IO FilePath

-- | Return the destination that the given symlink points to.
--   
--   An alias for System.Posix.Files.readSymbolicLink
--   
--   This function is only available on POSIX platforms.
readlink :: FilePath -> IO FilePath

-- | As readlink, but turns the result into an absolute path.
--   
--   This function is only available on POSIX platforms.
readlinkabs :: FilePath -> IO FilePath

-- | Reverse characters on each line (rev)
rev :: [String] -> [String]

-- | Reverse words on each line
--   
--   Reverse characters on each line (rev)
revW :: [String] -> [String]

-- | Sets an environment variable, replacing an existing one if it exists.
--   
--   Here's a sample ghci session to illustrate. First, let's see the
--   defaults for some variables:
--   
--   
--   Prelude HSH> runIO $ "echo $TERM, $LANG"
--   xterm, en_US.UTF-8
--   
--   
--   Now, let's set one:
--   
--   
--   Prelude HSH> runIO $ setenv [("TERM", "foo")] $ "echo $TERM, $LANG"
--   foo, en_US.UTF-8
--   
--   
--   Or two:
--   
--   
--   Prelude HSH> runIO $ setenv [("TERM", "foo")] $ setenv [("LANG", "de_DE.UTF-8")] $ "echo $TERM, $LANG"
--   foo, de_DE.UTF-8
--   
--   
--   We could also do it easier, like this:
--   
--   
--   Prelude HSH> runIO $ setenv [("TERM", "foo"), ("LANG", "de_DE.UTF-8")] $ "echo $TERM, $LANG"
--   foo, de_DE.UTF-8
--   
--   
--   It can be combined with unsetenv:
--   
--   
--   Prelude HSH> runIO $ setenv [("TERM", "foo")] $ unsetenv ["LANG"] $ "echo $TERM, $LANG"
--   foo,
--   
--   
--   And used with pipes:
--   
--   
--   Prelude HSH> runIO $ setenv [("TERM", "foo")] $ "echo $TERM, $LANG" -|- "tr a-z A-Z"
--   FOO, EN_US.UTF-8
--   
--   
--   See also unsetenv.
setenv :: ShellCommand cmd => [(String, String)] -> cmd -> EnvironCommand cmd

-- | Double space a file; add an empty line between each line.
space :: [String] -> [String]

-- | Inverse of double space; drop all empty lines.
unspace :: [String] -> [String]

-- | Reverse lines in a String (like Unix tac).
--   
--   Implemented as:
--   
--   
--   tac = reverse
--   
--   
--   See uniq.
tac :: [String] -> [String]

-- | Takes input, writes it to all the specified files, and passes it on.
--   This function does NOT buffer input.
--   
--   See also catFrom.
tee :: [FilePath] -> Channel -> IO Channel

-- | FIFO-safe version of tee.
--   
--   This call will BLOCK all threads on open until a reader connects.
--   
--   This function is only available on POSIX platforms.
teeFIFO :: [FilePath] -> Channel -> IO Channel

-- | Translate a character x to y, like:
--   
--   
--   tr 'e' 'f'
--   
--   
--   Or, in sed,
--   
--   
--   y//
--   
tr :: Char -> Char -> String -> String

-- | Delete specified character in a string.
trd :: Char -> String -> String

-- | Count number of words in a file (like wc -w)
wcW :: [String] -> [String]

-- | Count number of lines. Like wc -l
wcL :: [String] -> [String]

-- | Removes an environment variable if it exists; does nothing otherwise.
--   
--   See also setenv, which has a more extensive example.
unsetenv :: ShellCommand cmd => [String] -> cmd -> EnvironCommand cmd

-- | Remove duplicate lines from a file (like Unix uniq).
--   
--   Takes a String representing a file or output and plugs it through
--   lines and then nub to uniqify on a line basis.
uniq :: String -> String

-- | Copyright (c) 2006 John Goerzen, jgoerzen@complete.org
--   
--   Welcome to HSH, the Haskell Shell infrastructure.
--   
--   http://software.complete.org/hsh
--   
--   HSH is designed to let you mix and match shell expressions with
--   Haskell programs.
--   
--   Here are a few examples to get you started:
--   
--   
--   run $ "echo /etc/pass*" :: IO String
--    -> "/etc/passwd /etc/passwd-"
--   
--   runIO $ "ls -l" -|- "wc -l"
--    -> 12
--   
--   runIO $ "ls -l" -|- wcL
--    -> 12
--   
--   runIO $ ("ls", ["-l", "file with spaces.txt"])
--   glob "~jgoerzen" >>= cd . head
--   
--   
--   wcL is a pure Haskell function defined in "HSH.ShellEquivs.wcL" as:
--   
--   
--   wcL :: [String] -> [String]
--   wcL inp = [show $ genericLength inp]
--   
--   
--   Here's another example:
--   
--   
--   let countLines = (zipWith (\i line -> printf "%-5d %s" i line) 
--        [(1::Int)..])::([String] -> [String])
--   
--   runIO $ ("ls", ["-l"]) -|- countLines -|- filter (isSuffixOf "hs")
--     6     -rw-r--r-- 1 jgoerzen jgoerzen  1285 Jun  6 09:43 HSH.hs
--     11    -rw-r--r-- 1 jgoerzen jgoerzen   565 Jun  6 09:43 test.hs
--   
--   
--   To use HSH, you'll just want to import the HSH module. To learn more,
--   please see the information in HSH.Command and
--   HSH.ShellEquivs.
--   
--   You can run a command with HSH in several ways:
--   
--   
--   
- By using run in a context that expects IO (), which will
--   leave the final standard output going to the normal standard output of
--   the program
--   
- By using run in a context that expects a String, which will
--   capture standard output into a buffer and present it as a String
--   
- Any of the numerous other methods documented in
--   RunResult.
--   
- The shortcut functions runIO and runSL. runIO
--   lets you run a command and force the context IO (), which is a
--   frequently-useful shortcut when you don't care about the result.
--   runSL grabs the first line of output in the result.
--   
--   
--   You can then specify a command, which could be a single command or a
--   command joined together with pipes.
--   
--   There are many different items that make valid types; see the list of
--   instances of ShellCommand for a full list. Here are a few:
--   
--   
--   
- A simple bare string is passed to the shell for execution. The
--   shell will then typically expand wildcards, parse parameters,
--   etc.
--   
- A (String, [String]) tuple. The first item in the tuple
--   gives the name of a program to run, and the second gives its
--   arguments. The shell is never involved. This is ideal for passing
--   filenames, since there is no security risk involving special shell
--   characters.
--   
- A Haskell function. This function will accept input representing
--   its standard input and generate output to go to stdout. Function types
--   that are supported natively include (String -> String),
--   (String -> IO String), plus many more involving
--   ByteStrings and functions that take no input. See ShellCommand
--   for more.
--   
--   
--   Pipes can be constructed by using the -|- operator, as illustrated
--   above. It is quite possible to pipe data between Haskell functions and
--   shell commands at will.
--   
--   In addition, HSH.ShellEquivs provides a number of useful
--   pure-Haskell equivalents of regular shell commands.
--   
--   For more information, please consult the other modules in HSH as well
--   as the HSH wiki at:
--   
--   http://software.complete.org/hsh
module HSH
