HSH-2.1.3: Library to mix shell scripting with Haskell programs

Copyright Copyright (C) 2009 John Goerzen GNU LGPL, version 2.1 or above John Goerzen provisional portable None Haskell98

HSH.ShellEquivs

Description

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.

Synopsis

# Documentation

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.

Like catTo, but appends to the file.

The filename part of a path

bracketCD :: FilePath -> IO a -> IO a Source #

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.

catFrom :: [FilePath] -> Channel -> IO Channel Source #

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 .

Arguments

 :: Maybe Integer Maximum amount of data to transfer -> Channel Handle for input -> 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

Arguments

 :: Channel Handle to read from -> Maybe Integer Maximum amount of data to transfer -> Channel Handle for input (ignored) -> IO Channel

Generic version of catBytes; reads data from specified Channel, and ignores stdin.

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

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

cd :: FilePath -> IO () Source #

An alias for System.Directory.setCurrentDirectory.

Want to change to a user's home directory? Try this:

glob "~jgoerzen" >>= cd . head

See also bracketCD.

Split a list by a given character and select the nth list.

cut ' ' 2 "foo bar baz quux" -> "bar"

cutR :: [Integer] -> Char -> String -> String Source #

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.

The directory part of a path

echo :: Channelizable a => a -> Channel -> IO Channel Source #

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.

exit :: Int -> IO a Source #

Exits with the specified error code. 0 indicates no error.

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.

grep :: String -> [String] -> [String] Source #

Search for the string in the lines. Return those that match. Same as:

grep needle = filter (isInfixOf needle)

grepV :: String -> [String] -> [String] Source #

Search for the string in the lines. Return those that do NOT match.

egrep :: String -> [String] -> [String] Source #

Search for the regexp in the lines. Return those that match.

egrepV :: String -> [String] -> [String] Source #

Search for the regexp in the lines. Return those that do NOT match.

joinLines :: [String] -> [String] Source #

Join lines of a file

Convert a string to all lower case

Convert a string to all upper case

mkdir :: FilePath -> FileMode -> IO () Source #

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.

numberLines :: [String] -> [String] Source #

Number each line of a file

An alias for System.Directory.getCurrentDirectory.

Return the destination that the given symlink points to.

This function is only available on POSIX platforms.

As readlink, but turns the result into an absolute path.

This function is only available on POSIX platforms.

rev :: [String] -> [String] Source #

Reverse characters on each line (rev)

revW :: [String] -> [String] Source #

Reverse words on each line

Reverse characters on each line (rev)

setenv :: ShellCommand cmd => [(String, String)] -> cmd -> EnvironCommand cmd Source #

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.

space :: [String] -> [String] Source #

Double space a file; add an empty line between each line.

unspace :: [String] -> [String] Source #

Inverse of double space; drop all empty lines.

tac :: [String] -> [String] Source #

Reverse lines in a String (like Unix tac).

Implemented as:

tac = reverse

See uniq.

tee :: [FilePath] -> Channel -> IO Channel Source #

Takes input, writes it to all the specified files, and passes it on. This function does NOT buffer input.

See also catFrom.

teeFIFO :: [FilePath] -> Channel -> IO Channel Source #

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.

tr :: Char -> Char -> String -> String Source #

Translate a character x to y, like:

tr 'e' 'f'

Or, in sed,

y//

Delete specified character in a string.

wcW :: [String] -> [String] Source #

Count number of words in a file (like wc -w)

wcL :: [String] -> [String] Source #

Count number of lines. Like wc -l

unsetenv :: ShellCommand cmd => [String] -> cmd -> EnvironCommand cmd Source #

Removes an environment variable if it exists; does nothing otherwise.

See also setenv, which has a more extensive example.

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.