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Contents |
- Command Line Arguments
- Specific External Commands
- Miscellaneous
- Creating temporary files and directories
- Parsing and Composing Paths
- Processes, Pipes
- Ways of Calling External Programs
- Redirecting Input and Output
- Building Pipes
- Error Handling
- Calling a Shell, and Quoting for Shells
- Reexported Standard Library Stuff for Exception Handling
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Synopsis |
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module HsShellScript.Args | | realpath :: String -> IO String | | realpath_s :: String -> IO String | | symlink :: String -> String -> IO () | | is_symlink :: String -> IO Bool | | readlink :: String -> IO String | | du :: (Integral int, Read int) => int -> String -> IO int | | mkdir :: String -> IO () | | rmdir :: String -> IO () | | rm :: String -> IO () | | cd :: String -> IO () | | chmod :: [String] -> IO () | | chown :: [String] -> IO () | | cp :: String -> String -> IO () | | mv :: String -> String -> IO () | | pwd :: IO String | | mt_status :: IO (Int, Int) | | rename :: String -> String -> IO () | | force_rename :: String -> String -> IO () | | force_mv :: String -> String -> IO () | | force_cmd :: (String -> String -> IO ()) -> String -> String -> IO () | | readlink' :: String -> IO String | | fdupes :: [String] -> [String] -> IO [[[String]]] | | zeros :: Int -> Int -> String | | chomp :: String -> String | | lazy_contents :: String -> IO (String, Handle) | | contents :: String -> IO String | | path_exists :: String -> IO Bool | | path_exists' :: String -> IO Bool | | is_dir :: String -> IO Bool | | is_file :: String -> IO Bool | | getFileStatus' :: FilePath -> IO FileStatus | | fileAccess' :: FilePath -> Bool -> Bool -> Bool -> IO Bool | | tmp_file :: String -> IO FilePath | | tmp_dir :: String -> IO FilePath | | temp_file :: Int -> String -> String -> IO FilePath | | temp_dir :: Int -> String -> String -> IO FilePath | | temp_path :: Int -> String -> String -> IO FilePath | | with_tmp_file :: String -> (Handle -> IO a) -> IO a | | with_tmp_dir :: String -> (FilePath -> IO a) -> IO a | | with_temp_file :: Int -> String -> String -> (Handle -> IO a) -> IO a | | with_temp_dir :: Int -> String -> String -> (FilePath -> IO a) -> IO a | | slice_path :: String -> [String] | | unslice_path :: [String] -> String | | normalise_path :: String -> String | | slice_filename :: String -> [String] | | slice_filename' :: String -> [String] | | unslice_filename :: [String] -> String | | split_path :: String -> (String, String) | | dir_part :: String -> String | | filename_part :: String -> String | | unsplit_path :: (String, String) -> String | | split_filename :: String -> (String, String) | | split_filename' :: String -> (String, String) | | unsplit_filename :: (String, String) -> String | | split3 :: String -> (String, String, String) | | unsplit3 :: (String, String, String) -> String | | test_suffix :: String -> String -> Maybe String | | absolute_path :: String -> IO String | | absolute_path_by :: String -> String -> String | | absolute_path' :: String -> String -> String | | guess_dotdot_comps :: [String] -> Maybe [String] | | guess_dotdot :: String -> Maybe String | | call :: IO () -> IO () | | spawn :: IO () -> IO ProcessID | | run :: FilePath -> [String] -> IO () | | exec :: String -> [String] -> IO () | | execp :: String -> [String] -> IO () | | exece :: String -> [String] -> [(String, String)] -> IO () | | execpe :: String -> [String] -> [(String, String)] -> IO () | | echo :: (FilePath -> [String] -> IO ()) -> FilePath -> [String] -> IO () | | system_throw :: String -> IO () | | (->-) :: IO a -> FilePath -> IO a | | (->>-) :: IO a -> FilePath -> IO a | | (=>-) :: IO a -> FilePath -> IO a | | (=>>-) :: IO a -> FilePath -> IO a | | (-<-) :: IO a -> FilePath -> IO a | | (-&>-) :: IO a -> FilePath -> IO a | | (-&>>-) :: IO a -> FilePath -> IO a | | err_to_out :: IO () | | out_to_err :: IO () | | (-|-) :: IO a -> IO b -> IO a | | (=|-) :: IO a -> IO b -> IO a | | (-|=) :: IO a -> IO b -> IO b | | (=|=) :: IO a -> IO b -> IO b | | pipe_to :: String -> IO a -> IO () | | h_pipe_to :: IO a -> IO Handle | | pipe_from :: IO a -> IO String | | lazy_pipe_from :: IO a -> IO (String, IO ProcessStatus) | | h_pipe_from :: IO a -> IO Handle | | pipe_from2 :: IO a -> IO String | | lazy_pipe_from2 :: IO a -> IO (String, IO ProcessStatus) | | h_pipe_from2 :: IO a -> IO Handle | | pipes :: IO a -> Bool -> Bool -> Bool -> IO (Maybe Handle, Maybe Handle, Maybe Handle, ProcessID) | | errno :: IO Errno | | strerror :: Errno -> IO String | | perror' :: Errno -> String -> IO () | | perror :: String -> IO () | | abort :: (Typeable err) => (err -> String) -> IO a -> IO a | | failIO :: String -> IO a | | exitcode :: IO () -> IO ExitCode | | throwErrno' :: String -> Maybe Handle -> Maybe FilePath -> IO a | | show_ioerror :: IOError -> String | | mainwrapper :: IO a -> IO a | | shell_command :: String -> [String] -> String | | shell_quote :: String -> String | | quote0 :: String -> String | | quote :: String -> String |
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Command Line Arguments |
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module HsShellScript.Args |
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Specific External Commands |
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realpath |
:: String | path | -> IO String | noramlized, absolute path, with symbolic links expanded | Do a call to the realpath(3) system library function. This makes the path absolute, normalizes it and expands all symbolic links. In case of an
error (such as path not found), an IOError is thrown. The path is included in the IOError and can be accessed with ioeGetFileName from the
Haskell standard library IO. |
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realpath_s |
:: String | path | -> IO String | noramlized, absolute path, with symbolic links not expanded | Call the realpath program, with the -s
option. Return its output. See realpath(1). |
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symlink |
:: String | contents of the symlink (from) | -> String | path of the symlink (to) | -> IO () | | Make a symbolic link. This is the symlink(2) function. Any error results in an IOError thrown. The path of the intended symlink is included in
the IOError and
can be accessed with ioeGetFileName from the Haskell standard library IO. |
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is_symlink |
:: String | path | -> IO Bool | Whether the path is a symbolic link. |
Determine whether a path is a symbolic link. The path must exist in the file system. Otherwise, an IOError which makes isDoesNotExistError
(from the standard library IO) true will be thrown. Its GHC IOErrorType is NoSuchThing. However, the symlink may dangle. In this case the
result is True. This function calls readlink(2). Any error which may occur, results in an IOError thrown. The path is included in the IOError and
can be accessed with ioeGetFileName from the Haskell standard library IO. |
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readlink |
:: String | Path of the symbolic link | -> IO String | The link target - where the symbolic link points to | Determine the target of a symbolic link. This uses the readlink(2) system call. The result is a path which is either absolute, or relative to
the directory which the symlink is in. In case of an error, an IOError is thrown. The path is included and can be accessed with
IO.ioeGetFileName. Note that, if the path to the symlink ends with a slash, this path denotes the directory pointed to, not the symlink. In
this case the call to will fail because of "Invalid argument". |
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du |
:: (Integral int, Read int) | | => int | block size, this is the --block-size option. | -> String | path of the file or directory to determine the size of | -> IO int | size in blocks | Call the du program. See du(1). |
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mkdir |
:: String | path | -> IO () | | Create directory. This is Directory.createDirectory from the Haskell standard
library. In case of an error, the path is included in the IOError, which GHC's implementation neglects to do. |
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rmdir |
:: String | path | -> IO () | | Remove directory. This is
Directory.removeDirectory from the Haskell standard
library. In case of an error, the path is included in the IOError, which GHC's implementation neglects to do. |
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rm |
:: String | path | -> IO () | | Remove file. This is
Directory.removeFile from the Haskell standard
library. In case of an error, the path is included in the IOError, which GHC's implementation neglects to do. |
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cd |
:: String | path | -> IO () | | Change directory.This is an alias for
Directory.setCurrentDirectory from the Haskell standard
library. In case of an error, the path is included in the IOError, which GHC's implementation neglects to do. |
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chmod |
:: [String] | Command line arguments | -> IO () | | Execute binchmod chmod = run "/bin/chmod"
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chown |
:: [String] | Command line arguments | -> IO () | | Execute binchown chown = run "/bin/chown"
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cp |
:: String | source | -> String | destination | -> IO () | | Execute the cp program |
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mv |
:: String | source | -> String | destination | -> IO () | | Execute the mv program |
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pwd :: IO String |
Get program start working directory. This is the PWD environent
variable, which is kept by the shell (bash, at least). It records the
directory path in which the program has been started. Symbolic links in
this path aren't expanded. In this way, it differs from
getCurrentDirectory from the Haskell standard library. |
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mt_status |
:: IO (Int, Int) | file and block number | Run the command mt status for querying the tape drive status, and
parse its output. |
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rename |
:: String | Old path | -> String | New path or target directory | -> IO () | | The rename(2) system call to rename and/or move a file. The renameFile action from the Haskell standard library doesn't do it, because
the two paths may not refer to a directories. Failure results in an IOError thrown. The new path is included in
the IOError and
can be accessed with ioeGetFileName from the Haskell standard library IO. |
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force_rename |
:: String | Old path | -> String | New path or target directory | -> IO () | | Rename a file or directory, and cope with read only issues. This renames a file or directory, using rename, sets the necessary write permissions beforehand, and restores them afterwards. This is more
efficient than force_mv, because no external program needs to be called, but it can rename files only inside the same file system. See force_cmd
for a detailed description. The new path may be an existing directory. In this case, it is assumed that the old file is to be moved into this directory (like with mv). The
new path is then completed with the file name component of the old path. You won't get an "already exists" error. force_rename = force_cmd rename See force_cmd, rename.
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force_mv |
:: String | Old path | -> String | New path | -> IO () | | Move a file or directory, and cope with read only issues. This moves a file or directory, using the external command mv, sets the necessary write permissions beforehand, and restores them afterwards.
This is less efficient than force_rename, because the external program mv needs to be called, but it can move files between file systems. See
force_cmd for a detailed description. force_mv src tgt = force_cmd (\src tgt -> run "/bin/mv" ["--", src, tgt]) src tgt See force_cmd, force_mv.
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force_cmd |
:: (String -> String -> IO ()) | Command to execute after preparing the permissions | -> String | Old path | -> String | New path or target directory | -> IO () | | Call a command which moves a file or directory, and cope with read only issues. This function is for calling a command, which renames files. Beforehand, write permissions are set in order to enable the
operation, and afterwards the permissions are restored. The command is meant to be something like rename or run "/bin/mv". In order to change the name of a file or dirctory, but leave it in the super directory
it is in, the super directory must be writeable. In order to move a file or directory to a different super directory, both super directories and
the file/directory to be moved must be writeable. I don't know what this behaviour is supposed to be good for. This function copes with the case that the file/directory to be moved or renamed, or the super directories are read only. It makes the necessary
places writeable, calls the command, and makes them read only again, if they were before. The user needs the necessary permissions for changing the
corresponding write permissions. If an error occurs (such as file not found, or insufficient permissions), then the write permissions are restored
to the state before, before the exception is passed through to the caller. The command must take two arguments, the old path and the new path. It is expected to create the new path in the file system, such that the correct
write permissions of the new path can be set by force_cmd after executing it. The new path may be an existing directory. In this case, it is assumed that the old file is to be moved into this directory (like with mv). The
new path is completed with the file name component of the old path, before it is passed to the command, such that the command is supplied the
complete new path. Examples: force_cmd rename from to
force_cmd (\from to -> run "/bin/mv" ["-i", "-v", "--", from, to]) from to See force_rename, force_mv, rename.
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readlink' |
:: String | path of the symbolic link | -> IO String | target; where the symbolic link points to | Determine the target of a symbolic link. This uses the readlink(2) system call. The target is converted, such that it is relative to the current
working directory, if it isn't absolute. Note that, it the path to the symlink ends with a slash, this path denotes the directory pointed to, not the
symlink. In this case the call to readlink will fail with an IOError because of Invalid argument. In case of any
error, an IOError is thrown. The path is included in the IOError and can be accessed with ioeGetFileName from the
Haskell standard library IO. |
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fdupes |
:: [String] | Options for the fdupes program | -> [String] | Directories with files to compare | -> IO [[[String]]] | For each set of identical files, and each of the specified directories, the paths of the identical files in this
directory. | Call the fdupes program in order to find identical files. It outputs a
list of groups of file names, such that the files in each group are
identical. Each of these groups is further analysed by the fdupes
action. It is split to a list of lists of paths, such that each list
of paths corresponds to one of the directories which have been searched
by the fdupes program. If you just want groups of identical files, then apply map concat to the result. The paths are normalised (using normalise_path). |
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Miscellaneous |
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zeros |
:: Int | how many characters to fill up | -> Int | value to represent as a string | -> String | string representation of the value, using the specified number of characters | Format an Int with leading zeros. |
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chomp |
:: String | String to be chomped | -> String | same string, except for no newline characters at the end | Remove trailing newlines. This is silimar to perl's chomp procedure. |
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lazy_contents |
:: String | either the name of a file, or "-" | -> IO (String, Handle) | The contents of the file (or stdin) and the handle used to read it. | Get contents of a file or of stdin. This is hGetContents
applied either to a file or to stdin. A file name of
"-" designates stdin. The contents are read lazily as
the string is evaluated. The returned handle must be closed eventually, or the process will run
out of file handles. |
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contents |
:: String | either the name of a file, or "-" for stdin | -> IO String | the contents of the file or of standard input | Get contents of a file or of stdin eagerly. This is the
same as lazy_contents, except for the contents being
read immediately. |
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path_exists |
:: String | Path | -> IO Bool | Whether the path exists in the file system | Test for the existence of a path. This is the disjunction of
Directory.doesDirectoryExist and Directory.doesFileExist. For an dangling symlink, this will return False. |
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path_exists' |
:: String | Path | -> IO Bool | Whether the path exists in the file system | Test for the existence of a path. This uses System.Posix.Files.getFileStatus to determine whether the path exists in any form in the file system.
For a dangling symlink, the result is True. |
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is_dir |
:: String | Path | -> IO Bool | Whether the path exists and points to a directory. | Test if path points to a directory. This is a shortcut for
Directory.doesDirectoryExist. |
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is_file |
:: String | Path | -> IO Bool | Whether the path exists and points to a file. | Test if path points to a file. This is a shortcut for
Directory.doesFileExist. |
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getFileStatus' |
:: FilePath | Path of the file, whose status is to be queried | -> IO FileStatus | Status of the file | This is the System.Posix.Files.getFileStatus function from the GHC libraries, with improved error reporting. The GHC function doesn't include the
file name in the IOError when the call fails, making error messages much less useful. getFileStatus' rectifies this. See getFileStatus. |
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fileAccess' :: FilePath -> Bool -> Bool -> Bool -> IO Bool |
This is the System.Posix.Files.fileAccess function from the GHC libraries, with improved error reporting. The GHC function doesn't include the
file name in the IOError when the call fails, making error messages much less useful. fileAccess' rectifies this. See fileAccess. |
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Creating temporary files and directories |
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tmp_file |
:: String | Prefix for the path to generate. | -> IO FilePath | Path of the created file. | Create a temporary file. This will create a new, empty file, with read-write permissions for the user, and no permissons for the group and others.
The path consists of the specified prefix, a dot, and six random characters (digits and letters). tmp_file prefix = temp_file 6 (prefix ++ ".") "" See temp_file, tmp_dir, with_tmp_file. |
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tmp_dir |
:: String | Prefix for the path to generate. | -> IO FilePath | Path of the created directory. | Create a temporary directory. This will create a new directory, with read-write-execute permissions for the user (unless further restricted by the
process's umask), and no permissons for the group and others.
The path consists of the specified prefix, a dot, and six random characters (digits and letters). tmp_dir prefix = temp_dir 6 (prefix ++ ".") "" See temp_dir, tmp_file, with_tmp_dir. |
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temp_file |
:: Int | Number of random characters to intersperse. Must be large enough, such that most combinations can't already
exist. | -> String | Prefix for the path to generate. | -> String | Suffix for the path to generate. | -> IO FilePath | Path of the created file. | Create a temporary file. This will create a new, empty file, with a path which did not previously exist in the file system. The path consists
of the specified prefix, a sequence of random characters (digits and letters), and the specified suffix. The file is created with read-write
permissions for the user, and no permissons for the group and others. The ownership is set to the effective user ID of the process. The group
ownership is set either to the effective group ID of the process or to the group ID of the parent directory (depending on filesystem type and mount
options on Linux - see open(2) for details). See tmp_file, temp_dir, with_temp_file. |
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temp_dir |
:: Int | Number of random characters to intersperse. Must be large enough, such that most combinations can't already
exist. | -> String | Prefix for the path to generate. | -> String | Suffix for the path to generate. | -> IO FilePath | Generated path. | Create a temporary directory. This will create a new directory, with a path which did not previously exist in the file system. The path consists
of the specified prefix, a sequence of random characters (digits and letters), and the specified suffix. The directory is normally created with
read-write-execute permissions for the user, and no permissons for the group and others. But this may be further restricted by the process's umask
in the usual way. The newly created directory will be owned by the effective uid of the process. If the directory containing the it has the set group
id bit set, or if the filesystem is mounted with BSD group semantics, the new directory will inherit the group ownership from its parent;
otherwise it will be owned by the effective gid of the process. (See mkdir(2)) See tmp_dir, temp_file, with_temp_dir. |
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temp_path |
:: Int | Number of random characters to intersperse. Must be large enough, such that most combinations can't already
exist. | -> String | Prefix for the path to generate. | -> String | Suffix for the path to generate. | -> IO FilePath | Generated path. | Create a temporary path. This will generate a path which does not yet exist in the file system. It consists of the specified prefix, a
sequence of random characters (digits and letters), and the specified suffix. Avoid relying on the generated path not to exist in the file system. Or else you'll get a potential race condition, since some other process might
create the path after temp_path, before you use it. This is a security risk. The global random number generator (Random.randomRIO) is used to
generate the random characters. These might not be that random after all, and could potentially be guessed. Rather use temp_file or temp_dir. See temp_file, temp_dir. |
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with_tmp_file |
:: String | Prefix for the path to generate. | -> (Handle -> IO a) | Action to perform. | -> IO a | Returns the value returned by the action. | Create and open a temporary file, perform some action with it, and delete it afterwards. This is a front end to the tmp_file function. The file
and its path are created in the same way. The IO action is passed a handle of the new file. When it finishes - normally or with an exception -
the file is deleted. This works with all kinds of exceptions (ordinary or dynamic). See tmp_file, with_temp_file, with_tmp_dir. |
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with_tmp_dir |
:: String | Prefix for the path to generate. | -> (FilePath -> IO a) | Action to perform. | -> IO a | Returns the value returned by the action. | Create a temporary directory, perform some action with it, and delete it afterwards. This is a front end to the tmp_dir function. The directory
and its path are created in the same way. The IO action is passed the path of the new directory. When it finishes - normally or with an exception -
the directory is deleted. The action must clean up any files it creates inside the directory by itself. with_tmp_dir doesn't delete any files inside, so the directory could
be deleted. If the directory isn't empty, an IOError results (thrown by Directory.removeDirectory, with the path filled in). This works with all kinds of exceptions (ordinary or dynamic). See tmp_dir, with_temp_dir, with_tmp_file. |
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with_temp_file |
:: Int | Number of random characters to intersperse. Must be large enough, such that most combinations can't already
exist. | -> String | Prefix for the path to generate. | -> String | Suffix for the path to generate. | -> (Handle -> IO a) | Action to perform. | -> IO a | Returns the value returned by the action. | Create and open a temporary file, perform some action with it, and delete it afterwards. This is a front end to the temp_file function. The file
and its path are created in the same way. The IO action is passed a handle of the new file. When it finishes - normally or with an exception -
the file is deleted. This works with all kinds of exceptions (ordinary or dynamic). See temp_file, with_tmp_file, with_temp_dir. |
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with_temp_dir |
:: Int | Number of random characters to intersperse. Must be large enough, such that most combinations can't already
exist. | -> String | Prefix for the path to generate. | -> String | Suffix for the path to generate. | -> (FilePath -> IO a) | Action to perform. | -> IO a | Returns the value returned by the action. | Create a temporary directory, perform some action with it, and delete it afterwards. This is a front end to the temp_dir function. The directory
and its path are created in the same way. The IO action is passed the path of the new directory. When it finishes - normally or with an exception -
the directory is deleted. The action must clean up any files it creates inside the directory by itself. with_temp_dir doesn't delete any files inside, so the directory could
be deleted. If the directory isn't empty, an IOError results (thrown by Directory.removeDirectory, with the path filled in). This works with all kinds of exceptions (ordinary or dynamic). See temp_dir, with_tmp_dir, with_temp_file. |
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Parsing and Composing Paths |
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slice_path |
:: String | The path to be broken to components. | -> [String] | List of path components. | Split a path in components. Repeated "/" characters don't lead to empty
components. "." path components are removed. If the path is absolute, the first component
will start with "/". ".." components are left intact. They can't be simply
removed, because the preceding component might be a symlink. In this case,
realpath is probably what you need. The case that the path is empty, is probably an error. However, it is
treated like ".", yielding an empty path components list. Examples: slice_path "/" = ["/"]
slice_path "/foo/bar" = ["/foo","bar"]
slice_path "..//./" = [".."]
slice_path "." = [] See unslice_path, realpath, realpath_s.
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unslice_path |
:: [String] | List of path components | -> String | The path which consists of the supplied path components | Form a path from path components. This isn't the inverse
of slice_path, since unslice_path . slice_path
normalises the path. See slice_path.
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normalise_path |
:: String | Path to be normalised | -> String | Path in normalised form | Normalise a path. This is done by reducing repeated / characters to one, and removing
. path components. .. path components are left intact, because of possible symlinks. normalise_path = unslice_path . slice_path
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slice_filename |
:: String | Path | -> [String] | List of components the file name is made up of | Split a file name in components. This are the base file name and the
suffixes, which are separated by dots. If the name starts with a dot, it is
regarded as part of the base name. The result is a list of file name
components. The filename may be a path. In this case, everything up to the
last path component will be returned as part of the base file name. The
path gets normalised thereby. No empty suffixes are returned. If the file name contains several
consecutive dots, they are regared as part of the preceding file name
component. Concateneting the name components and adding dots, reproduces the
original name, with a normalised path:
concat . intersperse "." . slice_filename == normalise. Note that the last path component might be "..". Then it is not
possible to deduce the refered directory's name from the path. An IO
action for getting the real path is then necessary. Examples:
slice_filename "a.b//./.foo.tar.gz" == ["a.b/.foo","tar","gz"]
slice_filename ".x..y." == [".x.", "y."]
See unslice_filename, slice_filename'.
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slice_filename' |
:: String | File name without path | -> [String] | List of components the file name is made up of | This is a variant of slice_filename. It is like slice_filename, except for
being more efficient, and the filename must not contain any preceding path,
since this case isn't considered. See slice_filename, unslice_filename.
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unslice_filename |
:: [String] | List of file name components | -> String | Name of the file which consists of the supplied components | Form file name from file name components, interspersing dots. This is
the inverse of slice_filename, except for normalisation of any path. unslice_filename = concat . intersperse "." See slice_filename.
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split_path |
:: String | Path to be split | -> (String, String) | Directory and file name components of the path. The directory path is normalized. | Split a path in directory and file name. Only in the case that the
supplied path is empty, both parts are empty strings. Otherwise, "." is filled in
for the corresponding part, if necessary. Unless the path is empty,
concatenating the returned path and file name components with a slash in
between, makes a valid path to the file. split_path splits off the last path component. This
isn't the same as the text after the last /. Note that the last path component might be "..". Then it is not
possible to deduce the refered directory's name from the path. Then an IO
action for getting the real path is necessary. Examples: split_path "/a/b/c" == ("/a/b", "c")
split_path "foo" == (".", "foo")
split_path "foo/bar" == ("foo", "bar")
split_path "foo/.." == ("foo", "..")
split_path "." == (".", ".")
split_path "" == ("", "")
split_path "/foo" == ("/", "foo")
split_path "foo/" == (".", "foo")
split_path "foo/." == (".", "foo")
split_path "foo///./bar" == ("foo", "bar") See slice_path.
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dir_part :: String -> String |
Get the directory part of a path. dir_part = fst . split_path See split_path.
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filename_part :: String -> String |
Get the last path component of a path. filename_part = snd . split_path Examples: filename_part "foo/bar" == "bar"
filename_part "." == "." See split_path.
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unsplit_path |
:: (String, String) | Directory and file name | -> String | Path formed from the directory and file name parts | Inverse of split_path, except for normalisation. This concatenates two paths, and takes care of "." and empty paths. When the two components are the result of split_path, then unsplit_path
creates a normalised path. It is best documented by its definition: unsplit_path (".", "") = "."
unsplit_path ("", ".") = "."
unsplit_path (".", q) = q
unsplit_path ("", q) = q
unsplit_path (p, "") = p
unsplit_path (p, ".") = p
unsplit_path (p, q) = p ++ "/" ++ q Examples: unsplit_path ("", "") == ""
unsplit_path (".", "") == "."
unsplit_path (".", ".") == "."
unsplit_path ("foo", ".") == "foo" See split_path.
|
|
|
split_filename |
:: String | Path including the file name to be split | -> (String, String) | The normalised path with the file prefix, and the file suffix. | Split a file name in prefix and suffix. If there isn't any suffix in
the file name, then return an empty suffix. A dot at the beginning or at
the end is not regarded as introducing a suffix. The last path component is what is being split. This isn't the same as
splitting the string at the last dot. For instance, if the file name
doesn't contain any dot, dots in previous path component's aren't mistaken
as introducing suffixes. The path part is returned in normalised form. This means, "." components
are removed, and multiple "/"s are reduced to one. Note that there isn't any plausibility check performed on the suffix. If the file name doesn't have a suffix, but happens to contain a dot, then this
dot is mistaken as introducing a suffix. Examples: split_filename "path/to/foo.bar" = ("path/to/foo","bar")
split_filename "path/to/foo" = ("path/to/foo","")
split_filename "/path.to/foo" = ("/path.to/foo","")
split_filename "a///./x" = ("a/x","")
split_filename "dir.suffix/./" = ("dir","suffix")
split_filename "Photographie, Das 20. Jahrhundert (300 dpi)" = ("Photographie, Das 20", " Jahrhundert (300 dpi)") See slice_path, split_filename'
|
|
|
split_filename' |
:: String | Filename to be split | -> (String, String) | Base name and the last suffix | Variant of split_filename. This is a more efficient version
of split_filename, for the case that you know the string is
is a pure file name without any slashes. See split_filename.
|
|
|
unsplit_filename |
:: (String, String) | File name prefix and suffix | -> String | Path | Inverse of split_filename. Concatenate prefix and suffix, adding
a dot in between, iff the suffix is not empty. The path part of the prefix is
normalised. See split_filename.
|
|
|
split3 |
:: String | Path to split | -> (String, String, String) | Directory part, base file name part and suffix part | Split a path in directory, base file name and suffix.
|
|
|
unsplit3 |
:: (String, String, String) | Directory part, base file name part and suffix part | -> String | Path consisting of dir, base and suffix | Form path from directory, base file name and suffix parts.
|
|
|
test_suffix |
:: String | Suffix to split off | -> String | Path to test | -> Maybe String | Prefix without the suffix or Nothing | Test a path for a specific suffix and split it off. If the path ends with the suffix, then the result is Just
prefix, where prefix is the normalised path
without the suffix. Otherwise it's Nothing.
|
|
|
absolute_path |
:: String | The path to be made absolute | -> IO String | Absulte path | Make a path absolute, using the current working directory. This makes a relative path absolute with respect to the current
working directory. An absolute path is returned unmodified. The current working directory is determined with getCurrentDirectory
which means that symbolic links in it are expanded and the path is
normalised. This is different from pwd.
|
|
|
absolute_path_by |
:: String | The directory relative to which the path is made absolute | -> String | The path to be made absolute | -> String | Absolute path | Make a path absolute. This makes a relative path absolute with respect to a specified
directory. An absolute path is returned unmodified.
|
|
|
absolute_path' |
:: String | The path to be made absolute | -> String | The directory relative to which the path is made absolute | -> String | Absolute path | Make a path absolute. This makes a relative path absolute with respect to a specified
directory. An absolute path is returned unmodified. The order of the arguments can be confusing. You should rather use absolute_path_by. absolute_path' is included for backwards compatibility.
|
|
|
guess_dotdot_comps |
:: [String] | List of path components | -> Maybe [String] | In case the path could be transformed, the ".."-component free list of path components. | Guess the ".."-component free form of a path, specified as a list of path components, by syntactically removing them, along with the preceding
path components. This will produce
erroneous results when the path contains symlinks. If the path contains leading ".." components, or more ".." components than preceeding normal
components, then the ".." components can't be normalised away. In this case, the result is Nothing.
|
|
|
guess_dotdot |
:: String | Path to be normalised | -> Maybe String | In case the path could be transformed, the normalised, ".."-component free form of the path. | Guess the ".."-component free, normalised form of a path. The transformation is purely syntactic. ".." path components will be removed, along
with their preceding path components. This will produce
erroneous results when the path contains symlinks. If the path contains leading ".." components, or more ".." components than preceeding normal
components, then the ".." components can't be normalised away. In this case, the result is Nothing. guess_dotdot = fmap unslice_path . guess_dotdot_comps . slice_path
|
|
|
Processes, Pipes |
|
Ways of Calling External Programs |
|
call |
:: IO () | action to execute as a child process | -> IO () | | Execute an IO action as a separate process, and wait for it to finish.
Report errors as exceptions. The program forks a child process and performs the specified action.
Then it waits for the child process to finish. If it exits in any way
which indicates an error, the ProcessStatus is thrown as a dynamic
exception. It can then be catched with the catchDyn function from the
GHC Exception library. The waitpid call is done blockingly. It waits if the program has been
stopped. |
|
|
spawn |
:: IO () | Action to execute as a child process. | -> IO ProcessID | Process ID of the new process. | Execute an IO action as a separate process, and continue without waiting
for it to finish. The program forks a child process and performs the specified action.
The process ID is returned. It can be used in conjunction with
getProcessStatus. |
|
|
run :: FilePath -> [String] -> IO () |
Run an external program. This starts an external program as a child
process, and waits for it to finish. The executable is searched via the
PATH. If the program exits in a way which indicates an error, the
ProcessStatus is thrown as a dynamic exception, which can be catched
with the catchDyn function from the GHC Exception library. This is a frontend to call. See call. |
|
exec |
:: String | Full path to the executable | -> [String] | Command line arguments | -> IO () | | Execute an external program. This replaces the running process. The
path is not searched, and the environment is not changed. This is a shorthand for executeFile' ... False ... Nothing. See man page exec(3). |
|
|
execp |
:: String | Name or path of the executable | -> [String] | Command line arguments | -> IO () | | Execute an external program. This replaces the running process. The
PATH is searched, the environment is not changed. This is a shorthand for executeFile' ... True ... Nothing. See man page exec(3). |
|
|
exece |
:: String | Full path to the executable | -> [String] | Command line arguments | -> [(String, String)] | Environment | -> IO () | | Execute an external program. This replaces the running process. The
path is not searched. The environment is set to the specified value. This is a shorthand for executeFile' ... False ... (Just ...). See man page exec(3). |
|
|
execpe |
:: String | Name or path of the executable | -> [String] | Command line arguments | -> [(String, String)] | Environment | -> IO () | | Execute an external program. This replaces the running process. The
PATH is searched. The environment is set to the specified value. This is a shorthand for executeFile' ... True ... (Just ...). See man page exec(3). |
|
|
echo |
:: (FilePath -> [String] -> IO ()) | Action to perform | -> FilePath | Name or path of the executable to run | -> [String] | Command line arguments | -> IO () | | Print an action as a shell command, then perform it. This is used with actions such as run, exec or call. For instance,
echo run prog args is a variant of run prog args, which prints what
is being run, before running it. See run, call, exec. |
|
|
system_throw :: String -> IO () |
Call the shell to execute a command. In case of an error, throw the ProcessStatus (such as (Exited (ExitFailure ec))) as a dynamic exception.
This is like the Haskell standard library function system, except that error handling is brought in accordance with HsShellScript's scheme. exitcode . system_throw is the same as the system function, except that when the called shell is terminated or stopped by a signal, this still
leads to the ProcessStatus thrown as a dynamic exception. The Haskell library report says nothing about what happens in this case, when using the
system function. system_throw cmd = run "/bin/sh" ["-c", "--", cmd]
|
|
Redirecting Input and Output |
|
(->-) |
:: IO a | Action, whose output will be redirected | -> FilePath | File to redirect the output to | -> IO a | Result action | Redirect stdout to a file. This modifies the specified action, such
that the standard output is redirected to a file. This will also affect
all subsequently executed actions, if the action isn't called in a
separate process. The file will be overwritten, if it already exists. Example: call (exec "/path/to/foo" [] ->- "bar") See call, run, ->>-, =>-. |
|
|
(->>-) |
:: IO a | Action, whose output will be redirected | -> FilePath | File to redirect the output to | -> IO a | Result action | Redirect stdout to a file. This modifies the specified action, such
that the standard output is redirected to a file. This will also affect
all subsequently executed actions, if the action isn't called in a
separate process. If the file already exists, the output will be
appended. Example: call (exec "/path/to/foo" [] ->>- "bar") See call, run, '(->-)', '(=>>-)'. |
|
|
(=>-) |
:: IO a | Action, whose error output will be redirected | -> FilePath | File to redirect the error output to | -> IO a | Result action | Redirect stderr to a file. This modifies the specified action, such
that the standard error output is redirected to a file. This will also affect
all subsequently executed actions, if the action isn't called in a
separate process. The file will be overwritten, if it already exists. Example: call (exec "/path/to/foo" [] =>- "/dev/null") See call, run, '(->-)', '(=>>-)'. |
|
|
(=>>-) |
:: IO a | Action, whose error output will be redirected | -> FilePath | File to redirect the error output to | -> IO a | Result action | Redirect stderr to a file. This modifies the specified action, such
that the standard error output is redirected to a file. This will also affect
all subsequently executed actions, if the action isn't called in a
separate process. If the file already exists, the output will be
appended. Example: call (exec "/path/to/foo" [] =>>- "log") See call, run, '(->>-)', '(=>-)'. |
|
|
(-<-) :: IO a -> FilePath -> IO a |
Redirect stdin from a file. This modifies the specified action, such
that the standard input is read from a file. This will also affect
all subsequently executed actions, if the action isn't called in a
separate process. Example: call (exec "/path/to/foo" [] -<- "bar") See call, run, '(->-)', '(=>-)'. |
|
(-&>-) |
:: IO a | Action, whose output and error output will be redirected | -> FilePath | File to redirect to | -> IO a | Result action | Redirect both stdout and stderr to a file. This is equivalent to the shell's &> operator. If the file already exists, it will be overwritten.
This will also affect all subsequently executed actions, if the action isn't called in a separate process. Example: call (exec "/path/to/foo" [] -&>- "log") (-&>-) io path = (err_to_out >> io) (->-) path
|
|
|
(-&>>-) |
:: IO a | Action, whose output and error output will be redirected | -> FilePath | File to redirect to | -> IO a | Result action | Redirect both stdout and stderr to a file. If the file already exists, the output will be appended. This will also affect
all subsequently executed actions, if the action isn't called in a separate process. Example: call (exec "/path/to/foo" [] -&>>- "log") (-&>>-) io path = (err_to_out >> io) (->>-) path
|
|
|
err_to_out :: IO () |
Send the error output of the current process to its standard output. This will affect all subsequent IO actions. err_to_out = dupTo (intToFd 1) (intToFd 2) >> return ()
|
|
out_to_err :: IO () |
Send the standard output of the current process to its error output. This will affect all subsequent IO actions. out_to_err = dupTo (intToFd 2) (intToFd 1) >> return ()
|
|
Building Pipes |
|
(-|-) |
:: IO a | Action which won't be forked | -> IO b | Action which will be forked and connected with a pipe | -> IO a | Result action | Build left handed pipe of stdout. "p -|- q" builds an IO action from the two IO actions p and q.
q is executed in an external process. The standard output of p is sent
to the standard input of q through a pipe. The result action consists
of forking off q (connected with a pipe), and p. The result action does not run p in a separate process. So, the pipe
itself can be seen as a modified action p, forking a connected q.
Normally, the pipe itself will be forked, too. The pipe is called "left
handed", because p has this property, and not q. The exit code of q is silently ignored. The process ID of the forked
copy of q isn't returned to the caller, so it's lost. Example: call (exec "/usr/bin/foo" [] -|- exec "/usr/bin/bar" []) See call, '(=|-)', '(-|=)'. |
|
|
(=|-) |
:: IO a | Action which won't be forked | -> IO b | Action which will be forked and connected with a pipe | -> IO a | Result action | Build left handed pipe of stderr. "p =|- q" builds an IO action from the two IO actions p and q.
q is executed in an external process. The standard error output of p is sent
to the standard input of q through a pipe. The result action consists
of forking off q (connected with a pipe), and p. The result action does not run p in a separate process. So, the pipe
itself can be seen as a modified action p, forking a connected q.
Normally, the pipe itself will be forked, too. The pipe is called "left
handed", because p has this property, and not q. The exit code of q is silently ignored. The process ID of the forked
copy of q isn't returned to the caller, so it's lost. Example: call (exec "/usr/bin/foo" [] =|- exec "/usr/bin/bar" []) See call, '(-|-)', '(-|=)'. |
|
|
(-|=) |
:: IO a | Action which will be forked and connected with a pipe | -> IO b | Action which won't be forked | -> IO b | Result action | Build right handed pipe of stdout. "p -|= q" builds an IO action from the two IO actions p and q.
p is executed in an external process. The standard output of p is sent
to the standard input of q through a pipe. The result action consists
of forking off p (connected with a pipe), and q. The result action does not run q in a separate process. So, the pipe
itself can be seen as a modified action q, forking a connected p.
Normally, the pipe itself will be forked, too. The pipe is called "right
handed", because q has this property, and not p. The exit code of p is silently ignored. The process ID of the forked
copy of q isn't returned to the caller, so it's lost. Example: call (exec "/usr/bin/foo" [] -|= exec "/usr/bin/bar" []) See call, '(=|-)', '(=|=)'. |
|
|
(=|=) |
:: IO a | Action which will be forked and connected with a pipe | -> IO b | Action which won't be forked | -> IO b | Result action | Build right handed pipe of stderr. "p =|= q" builds an IO action from the two IO actions p and q.
p is executed in an external process. The standard error output of p is sent
to the standard input of q through a pipe. The result action consists
of forking off p (connected with a pipe), and q. The result action does not run q in a separate process. So, the pipe
itself can be seen as a modified action q, forking a connected p.
Normally, the pipe itself will be forked, too. The pipe is called "right
handed", because q has this property, and not p. The exit code of p is silently ignored. The process ID of the forked
copy of q isn't returned to the caller, so it's lost. Example: call (exec "/usr/bin/foo" [] =|= exec "/usr/bin/bar" []) See call, '(=|-)', '(-|=)'. |
|
|
pipe_to |
:: String | Text to pipe | -> IO a | Action to run as a separate process, and to pipe to | -> IO () | | Run an IO action as a separate process, and pipe some text to its
standard input. The pipe is closed afterwards. Example: pipe_to "blah" $ exec "/usr/bin/foo" ["bar"] See call, run, -<-, h_pipe_to. |
|
|
h_pipe_to |
:: IO a | Action to run as a separate process, and to pipe to | -> IO Handle | | Run an IO action as a separate process, and connect to its standard input
with a pipe. Example: h <- h_pipe_to $ exec "/usr/bin/foo" ["bar"] See call, run, -<-, pipe_to, pipe_from, pipe_from2. |
|
|
pipe_from |
:: IO a | Action to run as a separate process | -> IO String | The called program's standard output. | Run an IO action as a separate process, and read its standard
output immediately. This is like the backquote feature of shells. If the process exits in any way which indicates an error, the
ProcessStatus is thrown as a dynamic exception. Example: txt <- pipe_from $ exec "/usr/bin/foo" ["bar"] See call, run, -<-, pipe_to, pipe_from2 |
|
|
lazy_pipe_from |
:: IO a | Action to run as a separate process | -> IO (String, IO ProcessStatus) | The action's lazy output and the close action | Run an IO action as a separate process, and lazily read its standard
output. This is like the backquote feature of shells. The output is read
lazily, as the returned string is evaluated. The result is the process' output and a close action, which must be
called after the caller has finished reading. It closes the pipe
and waits for the child process to finish. If not all of the program's
output has been read yet, the operating system will send it a
SIGPIPE signal, which causes the child to terminate, unless it
catches this signal. The close action returns the child process'
process status, which is either Exited exitCode or
Terminated signal. Example: do (txt,close) <- lazy_pipe_from $ exec "/usr/bin/foo" ["bar"]
...
close See call, run, -<-, pipe_to, pipe_from2 |
|
|
h_pipe_from |
:: IO a | Action to run as a separate process | -> IO Handle | | Run an IO action as a separate process, and connect to its standard output
with a pipe. Example: h <- h_pipe_from $ exec "/usr/bin/foo" ["bar"] See call, run, -<-, pipe_to, pipe_from2 |
|
|
pipe_from2 |
:: IO a | Action to run as a separate process | -> IO String | The called program's standard error output. | Run an IO action as a separate process, and read its standard
error output immediately. If the process exits in any way which indicates an error, the
ProcessStatus is thrown as a dynamic exception. Example: err <- pipe_from $ exec "/usr/bin/foo" ["bar"] See call, run, -<-, pipe_to, pipe_from |
|
|
lazy_pipe_from2 |
:: IO a | Action to run as a separate process | -> IO (String, IO ProcessStatus) | The action's lazy error output and the close action | Run an IO action as a separate process, and lazily read its standard
error output. The output is read lazily, as the returned string is
evaluated. The result is the process' error output and a close action, which must
be called after the caller has finished reading. It closes the pipe and
waits for the child process to finish. If not all of the program's
error output has been read yet, the operating system will send it a SIGPIPE
signal, which causes the child to terminate, unless it catches this
signal. The close action returns the child process' process status,
which is either Exited exitCode or Terminated signal. Example: do (err,close) \<- lazy_pipe_from2 $ exec "/usr/bin/foo" ["bar"]
...
close See call, run, -<-, pipe_to, pipe_from |
|
|
h_pipe_from2 |
:: IO a | Action to run as a separate process, and to connect with a pipe | -> IO Handle | | Run an IO action as a separate process, and connect to its standard
error output with a pipe. Example: h <- h_pipe_from2 $ exec "/usr/bin/foo" ["bar"] See call, run, -<-, pipe_to, pipe_from. |
|
|
pipes |
:: IO a | Action to run in a new process | -> Bool | Whether to make stdin pipe | -> Bool | Whether to make stdout pipe | -> Bool | Whether to make stderr pipe | -> IO (Maybe Handle, Maybe Handle, Maybe Handle, ProcessID) | Pipes to the new process's stdin, stdout and stderr, if applicable; and its process id. | Run an IO action as a separate process, and optionally connect to its
standard input, its standard output and its standard error output with
pipes. See pipe_from, pipe_from2, pipe_to. |
|
|
Error Handling |
|
errno |
:: IO Errno | errno value | Read the global system error number. This is the POSIX errno value. This function is redundant. Use Foreign.C.Error.getErrno instead. |
|
|
strerror |
:: Errno | errno value | -> IO String | Corresponding error message | Generate an error message from an errno value. This is the POSIX
strerror system library function. See the man page strerror(3). |
|
|
perror' |
:: Errno | errno error number | -> String | Text to precede the message, separated by ": " | -> IO () | | Print error message corresponding to the specified errno error
number. This is like to the POSIX system library function perror. See the man page perror(3). |
|
|
perror |
:: String | Text to precede the message, separated by ": " | -> IO () | | Print error message corresponding to the global errno error
number. This is the same as the POSIX system library function perror. See the man page perror(3). |
|
|
abort |
:: (Typeable err) | | => (err -> String) | Error message generation function | -> IO a | IO action to monitor | -> IO a | Same action, but abort with error message in case of user exception | Execute the supplied action. In case of an error, print a message and
exit. An error is a dynamic exception, thrown using throwDyn as a type which is
instance of Typeable. The type err is supposed to be a specific type used
for specific errors. The program is terminated with exitFailure.
|
|
|
failIO :: String -> IO a |
Print a message to stderr and exit with an exit code
indicating an error. failIO msg = hPutStrLn stderr msg >> exitFailure |
|
exitcode |
:: IO () | Action to modify | -> IO ExitCode | Modified action | Return the exit code, instead of throwing it as a dynamic exception. This is used to modify the error reporting behaviour of an IO action. It
is used in conjunction with run or call. Normally, they throw a
process status, which indicates any error as a dynamic exception. After
exitcode has been applied, only termination by a signal causes an exception
to be thrown. An exit code which indicates failure, instead is returned. Example: ec <- exitcode $ run "foo" ["bar"] See run, call. |
|
|
throwErrno' |
:: String | Description of the location where the error occurs in the program | -> Maybe Handle | Optional handle | -> Maybe FilePath | Optional file name (for failing operations on files) | -> IO a | | Create and throw an IOError from the current errno value, an optional handle and an optional file name. This is an extended version of the Foreign.C.Error.throwErrno function
from the GHC libraries, which additionally allows to specify a handle and a file
name to include in the IOError thrown. See Foreign.C.Error.throwErrno, Foreign.C.Error.errnoToIOError. |
|
|
show_ioerror :: IOError -> String |
Convert an IOError to a string. There is an instance declaration of IOError in Show in the GHC.IOBase library, but show_ioerror produces a more readable, and more
complete, message. |
|
mainwrapper |
:: IO a | Should be main | -> IO a | Wrapped main | Error reporting wrapper for the main function. This catches any
HsShellScript generated exception, and IOErrors from the IO library. prints
an error message and exits with exitFailure. The main function
typically looks like this: main = mainwrapper main' The exceptions caught are ArgError, ProcessStatus, IOError.
|
|
|
Calling a Shell, and Quoting for Shells |
|
shell_command |
:: String | name or path of the executable | -> [String] | command line arguments | -> String | shell command | Generate command (for a shell) which corresponds to the specified program
name and argument list. The program name and arguments are the usual
parameters for calling an external program, like when using
runProcess or run. The generated shell command
would achieve the same effect. The name and the arguments are properly
quoted. |
|
|
shell_quote :: String -> String |
Quote shell metacharacters. This function quotes strings, such that they are not misinterpreted by
the shell. It tries to be friendly to a human reader - when special
characters are present, then the string is quoted with double quotes. If
not, it is left unchanged. The list of exacly which characters need to be quoted has been taken
from the bash source code. Bash in turn, implements POSIX 1003.2. So the
result produced should be correct. From the bash info pages:
"... the rules for evaluation and quoting are taken from the POSIX
1003.2 specification for the standard Unix shell." See quote. |
|
quote0 :: String -> String |
Quote special characters inside a string for the shell This quotes special characters inside a string, such that it is
recognized as one string by the shell when enclosed in double quotes.
Doesn't add the double quotes. See quote, shell_quote. |
|
quote :: String -> String |
Quote a string for the shell This encloses a string in double quotes and quotes any special
characters inside, such that it will be recognized as one string by a
shell. The double quotes are added even when they aren't needed for this
purpose. See quote0, shell_quote. |
|
Reexported Standard Library Stuff for Exception Handling |
|
Produced by Haddock version 0.4 |