{- Shell Equivalents Copyright (C) 2004-2008 John Goerzen Please see the COPYRIGHT file -} {- | Module : HSH.ShellEquivs Copyright : Copyright (C) 2008 John Goerzen License : GNU LGPL, version 2.1 or above Maintainer : John Goerzen Stability : provisional Portability: portable Copyright (c) 2006-2008 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( abspath, appendTo, basename, bracketCD, catFrom, catTo, cd, cut, cutR, dirname, echo, exit, glob, grep, grepV, egrep, egrepV, joinLines, lower, upper, mkdir, numberLines, pwd, readlink, readlinkabs, rev, revW, space, unspace, tac, tee, tr, trd, wcW, wcL, uniq, ) where import Data.List (genericLength, intersperse, isInfixOf, nub) import Data.Char (toLower, toUpper) import Text.Regex (matchRegex, mkRegex) import Text.Printf (printf) import Control.Monad (foldM) import System.Directory hiding (createDirectory) -- import System.FilePath (splitPath) import System.Posix.Files (getFileStatus, isSymbolicLink, readSymbolicLink) import System.Posix.User (getEffectiveUserName, getUserEntryForName, homeDirectory) import System.Posix.Directory (createDirectory) import System.Posix.Types (FileMode()) import System.Path (absNormPath, bracketCWD) import System.Exit import qualified System.Path.Glob as Glob (glob) {- | Return the absolute path of the arg. Raises an error if the computation is impossible. -} abspath :: FilePath -> IO FilePath abspath inp = do p <- pwd case absNormPath p inp of Nothing -> fail $ "Cannot make " ++ show inp ++ " absolute within " ++ show p Just x -> return x {- | The filename part of a path -} basename :: FilePath -> FilePath basename = snd . splitpath {- | The directory part of a path -} dirname :: FilePath -> FilePath dirname = fst . splitpath {- | 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 bracketCD = bracketCWD {- | 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 read. Unlike the shell cat, @-@ may be given twice. However, if it is, you will be forcing Haskell to buffer the input. Note: buffering behavior here is untested. -} catFrom :: [FilePath] -> String -> IO String catFrom fplist inp = do r <- foldM foldfunc "" fplist return r where foldfunc accum fp = case fp of "-" -> return (accum ++ inp) fn -> do c <- readFile fn return (accum ++ c) {- | Takes input, writes it to the specified file, and does not pass it on. See also 'tee'. -} catTo :: FilePath -> String -> IO String catTo fp inp = do writeFile fp inp return "" {- | Like 'catTo', but appends to the file. -} appendTo :: FilePath -> String -> IO String appendTo fp inp = do appendFile fp inp return "" {- | 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 () cd = setCurrentDirectory {- | Split a list by a given character and select the nth list. > cut ' ' 2 "foo bar baz quux" -> "bar" -} cut :: Integer -> Char -> String -> String cut pos = cutR [pos] {- | 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 cutR nums delim z = drop 1 $ concat [delim:x | (x, y) <- zip string [0..], elem y nums] where string = split delim z {- | Takes a string and sends it on as standard output. The input to this function is never read. -} echo :: String -> String -> String echo inp _ = inp {- | Search for the regexp in the lines. Return those that match. -} egrep :: String -> [String] -> [String] egrep pat = filter (ismatch regex) where regex = mkRegex pat ismatch r inp = case matchRegex r inp of Nothing -> False Just _ -> True {- | Search for the regexp in the lines. Return those that do NOT match. -} egrepV :: String -> [String] -> [String] egrepV pat = filter (not . ismatch regex) where regex = mkRegex pat ismatch r inp = case matchRegex r inp of Nothing -> False Just _ -> True {- | Exits with the specified error code. 0 indicates no error. -} exit :: Int -> IO a exit code | code == 0 = exitWith ExitSuccess | otherwise = exitWith (ExitFailure code) {- | 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] glob inp@('~':remainder) = catch expanduser (\_ -> Glob.glob inp) where (username, rest) = span (/= '/') remainder expanduser = do lookupuser <- if username /= "" then return username else getEffectiveUserName ue <- getUserEntryForName lookupuser Glob.glob (homeDirectory ue ++ rest) glob x = Glob.glob x {- | Search for the string in the lines. Return those that match. Same as: > grep needle = filter (isInfixOf needle) -} grep :: String -> [String] -> [String] grep = filter . isInfixOf {- | Search for the string in the lines. Return those that do NOT match. -} grepV :: String -> [String] -> [String] grepV needle = filter (not . isInfixOf needle) -- | Join lines of a file joinLines :: [String] -> [String] joinLines = return . concat {- | Creates the given directory. A value of 0o755 for mode would be typical. An alias for System.Posix.Directory.createDirectory. -} mkdir :: FilePath -> FileMode -> IO () mkdir = createDirectory {- | Number each line of a file -} numberLines :: [String] -> [String] numberLines = zipWith (printf "%3d %s") [(1::Int)..] {- | An alias for System.Directory.getCurrentDirectory. -} pwd :: IO FilePath pwd = getCurrentDirectory {- | Return the destination that the given symlink points to. An alias for System.Posix.Files.readSymbolicLink -} readlink :: FilePath -> IO FilePath readlink fp = do issym <- (getFileStatus fp >>= return . isSymbolicLink) if issym then readSymbolicLink fp else return fp {- | As 'readlink', but turns the result into an absolute path. -} readlinkabs :: FilePath -> IO FilePath readlinkabs inp = do issym <- (getFileStatus inp >>= return . isSymbolicLink) if issym then do rl <- readlink inp case absNormPath (dirname inp) rl of Nothing -> fail $ "Cannot make " ++ show rl ++ " absolute within " ++ show (dirname inp) Just x -> return x else abspath inp {- | Reverse characters on each line (rev) -} rev, revW :: [String] -> [String] rev = map reverse {- | Reverse words on each line -} revW = map (unwords . reverse . words) {- | Reverse lines in a String (like Unix tac). Implemented as: > tac = reverse See 'uniq'. -} tac :: [String] -> [String] tac = reverse {- | Takes input, writes it to all the specified files, and passes it on. This function buffers the input. See also 'catFrom'. -} tee :: [FilePath] -> String -> IO String tee [] inp = return inp tee (x:xs) inp = writeFile x inp >> tee xs inp {- | Translate a character x to y, like: >tr 'e' 'f' Or, in sed, >y// -} tr :: Char -> Char -> String -> String tr a b = map (\x -> if x == a then b else x) {- | Delete specified character in a string. -} trd :: Char -> String -> String trd = filter . (/=) {- | 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 uniq = unlines . nub . lines {- | Double space a file -} space, unspace :: [String] -> [String] space = intersperse "" {- | Inverse of double space; drop empty lines -} unspace = filter (not . null) {- | Convert a string to all upper or lower case -} lower, upper :: String -> String lower = map toLower upper = map toUpper {- | Count number of lines. wc -l -} wcL, wcW :: [String] -> [String] wcL inp = [show (genericLength inp :: Integer)] {- | Count number of words in a file (like wc -w) -} wcW inp = [show ((genericLength $ words $ unlines inp) :: Integer)] {- Utility function. > split ' ' "foo bar baz" -> ["foo","bar","baz"] -} split :: Char -> String -> [String] split c s = case rest of [] -> [chunk] _:rst -> chunk : split c rst where (chunk, rest) = break (==c) s -- TODO: Perhaps simplify to make use of split splitpath :: String -> (String, String) splitpath "" = (".", ".") splitpath "/" = ("/", "/") splitpath p | last p == '/' = splitpath (init p) | not ('/' `elem` p) = (".", p) | head p == '/' && length (filter (== '/') p) == 1 = ("/", tail p) | otherwise = (\(base, dir) -> (reverse (tail dir), reverse base)) (break (== '/') (reverse p))