unix-2.7.2.2: POSIX functionality

System.Posix.Files.ByteString

Description

Functions defined by the POSIX standards for manipulating and querying the file system. Names of underlying POSIX functions are indicated whenever possible. A more complete documentation of the POSIX functions together with a more detailed description of different error conditions are usually available in the system's manual pages or from http://www.unix.org/version3/online.html (free registration required).

When a function that calls an underlying POSIX function fails, the errno code is converted to an IOError using errnoToIOError. For a list of which errno codes may be generated, consult the POSIX documentation for the underlying function.

Synopsis

# File modes

Combines the two file modes into one that contains modes that appear in either.

Combines two file modes into one that only contains modes that appear in both.

No permissions.

Owner has write permission.

Owner has execute permission.

Owner has read, write and execute permission.

Group has write permission.

Group has execute permission.

Group has read, write and execute permission.

Others have write permission.

Others have execute permission.

Others have read, write and execute permission.

Set user ID on execution.

Set group ID on execution.

Owner, group and others have read and write permission.

Owner, group and others have read, write and execute permission.

## Setting file modes

setFileMode path mode changes permission of the file given by path to mode. This operation may fail with throwErrnoPathIfMinus1_ if path doesn't exist or if the effective user ID of the current process is not that of the file's owner.

Note: calls chmod.

setFdMode :: Fd -> FileMode -> IO () Source #

setFdMode fd mode acts like setFileMode but uses a file descriptor fd instead of a FilePath.

Note: calls fchmod.

setFileCreationMask mode sets the file mode creation mask to mode. Modes set by this operation are subtracted from files and directories upon creation. The previous file creation mask is returned.

Note: calls umask.

## Checking file existence and permissions

fileAccess name read write exec checks if the file (or other file system object) name can be accessed for reading, writing and/or executing. To check a permission set the corresponding argument to True.

Note: calls access.

Checks for the existence of the file.

Note: calls access.

# File status

POSIX defines operations to get information, such as owner, permissions, size and access times, about a file. This information is represented by the FileStatus type.

Note: see chmod.

## Obtaining file status

getFileStatus path calls gets the FileStatus information (user ID, size, access times, etc.) for the file path.

Note: calls stat.

getFdStatus fd acts as getFileStatus but uses a file descriptor fd.

Note: calls fstat.

Acts as getFileStatus except when the RawFilePath refers to a symbolic link. In that case the FileStatus information of the symbolic link itself is returned instead of that of the file it points to.

Note: calls lstat.

## Querying file status

ID of the device on which this file resides.

inode number

File mode (such as permissions).

Number of hard links to this file.

ID of owner.

ID of group.

Describes the device that this file represents.

Size of the file in bytes. If this file is a symbolic link the size is the length of the pathname it contains.

Time of last access.

Time of last modification.

Time of last status change (i.e. owner, group, link count, mode, etc.).

Time of last access in sub-second resolution.

Time of last modification in sub-second resolution.

Time of last status change (i.e. owner, group, link count, mode, etc.) in sub-second resolution.

Checks if this file is a block device.

Checks if this file is a character device.

Checks if this file is a named pipe device.

Checks if this file is a regular file device.

Checks if this file is a directory device.

Checks if this file is a symbolic link device.

Checks if this file is a socket device.

# Creation

createNamedPipe fifo mode creates a new named pipe, fifo, with permissions based on mode. May fail with throwErrnoPathIfMinus1_ if a file named name already exists or if the effective user ID of the current process doesn't have permission to create the pipe.

Note: calls mkfifo.

createDevice path mode dev creates either a regular or a special file depending on the value of mode (and dev). mode will normally be either blockSpecialMode or characterSpecialMode. May fail with throwErrnoPathIfMinus1_ if a file named name already exists or if the effective user ID of the current process doesn't have permission to create the file.

Note: calls mknod.

createLink old new creates a new path, new, linked to an existing file, old.

Note: calls link.

removeLink path removes the link named path.

Note: calls unlink.

createSymbolicLink file1 file2 creates a symbolic link named file2 which points to the file file1.

Symbolic links are interpreted at run-time as if the contents of the link had been substituted into the path being followed to find a file or directory.

Note: calls symlink.

Reads the RawFilePath pointed to by the symbolic link and returns it.

Note: calls readlink.

# Renaming files

rename old new renames a file or directory from old to new.

Note: calls rename.

# Changing file ownership

setOwnerAndGroup path uid gid changes the owner and group of path to uid and gid, respectively.

If uid or gid is specified as -1, then that ID is not changed.

Note: calls chown.

Acts as setOwnerAndGroup but uses a file descriptor instead of a FilePath.

Note: calls fchown.

Acts as setOwnerAndGroup but does not follow symlinks (and thus changes permissions on the link itself).

Note: calls lchown.

# Changing file timestamps

setFileTimes path atime mtime sets the access and modification times associated with file path to atime and mtime, respectively.

Note: calls utime.

Like setFileTimes but timestamps can have sub-second resolution.

Note: calls utimensat or utimes.

Like setFileTimesHiRes but uses a file descriptor instead of a path. This operation is not supported on all platforms. On these platforms, this function will raise an exception.

Note: calls futimens or futimes.

Since: unix-2.7.0.0

Like setFileTimesHiRes but does not follow symbolic links. This operation is not supported on all platforms. On these platforms, this function will raise an exception.

Note: calls utimensat or lutimes.

touchFile path sets the access and modification times associated with file path to the current time.

Note: calls utime.

touchFd :: Fd -> IO () Source #

Like touchFile but uses a file descriptor instead of a path. This operation is not supported on all platforms. On these platforms, this function will raise an exception.

Note: calls futimes.

Since: unix-2.7.0.0

Like touchFile but does not follow symbolic links. This operation is not supported on all platforms. On these platforms, this function will raise an exception.

Note: calls lutimes.

# Setting file sizes

Truncates the file down to the specified length. If the file was larger than the given length before this operation was performed the extra is lost.

Note: calls truncate.

setFdSize :: Fd -> FileOffset -> IO () Source #

Acts as setFileSize but uses a file descriptor instead of a FilePath.

Note: calls ftruncate.

# Find system-specific limits for a file

getPathVar var path obtains the dynamic value of the requested configurable file limit or option associated with file or directory path. For defined file limits, getPathVar returns the associated value. For defined file options, the result of getPathVar is undefined, but not failure.

Note: calls pathconf.

getFdPathVar var fd obtains the dynamic value of the requested configurable file limit or option associated with the file or directory attached to the open channel fd. For defined file limits, getFdPathVar returns the associated value. For defined file options, the result of getFdPathVar is undefined, but not failure.

Note: calls fpathconf.