Ubuntu Manpage: file - Manipulate file names and attributes

NAME

       file - Manipulate file names and attributes

SYNOPSIS

       file option name ?arg arg ...?
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DESCRIPTION

This command provides several operations on a file's name or attributes. Name is the name of a file; if
it starts with a tilde, then tilde substitution is done before executing the command (see the manual
entry for filename for details). Option indicates what to do with the file name. Any unique
abbreviation for option is acceptable. The valid options are:

file atime name ?time?
Returns a decimal string giving the time at which file name was last accessed. If time is
specified, it is an access time to set for the file. The time is measured in the standard POSIX
fashion as seconds from a fixed starting time (often January 1, 1970). If the file doesn't exist
or its access time cannot be queried or set then an error is generated. On Windows, FAT file
systems do not support access time.

file attributes name

file attributes name ?option?

file attributes name ?option value option value...?
This subcommand returns or sets platform specific values associated with a file. The first form
returns a list of the platform specific flags and their values. The second form returns the value
for the specific option. The third form sets one or more of the values. The values are as follows:

On Unix, -group gets or sets the group name for the file. A group id can be given to the command,
but it returns a group name. -owner gets or sets the user name of the owner of the file. The
command returns the owner name, but the numerical id can be passed when setting the owner.
-permissions sets or retrieves the octal code that chmod(1) uses. This command does also has
limited support for setting using the symbolic attributes for chmod(1), of the form
[ugo]?[[+-=][rwxst],[...]], where multiple symbolic attributes can be separated by commas
(example: u+s,go-rw add sticky bit for user, remove read and write permissions for group and
other). A simplified ls style string, of the form rwxrwxrwx (must be 9 characters), is also
supported (example: rwxr-xr-t is equivalent to 01755).

On Windows, -archive gives the value or sets or clears the archive attribute of the file. -hidden
gives the value or sets or clears the hidden attribute of the file. -longname will expand each
path element to its long version. This attribute cannot be set. -readonly gives the value or sets
or clears the readonly attribute of the file. -shortname gives a string where every path element
is replaced with its short (8.3) version of the name. This attribute cannot be set. -system gives
or sets or clears the value of the system attribute of the file.

file channels ?pattern? 2
If pattern isn't specified, returns a list of names of all registered open channels in this 2
interpreter. If pattern is specified, only those names matching pattern are returned. Matching 2
is determined using the same rules as for string match.

file copy ?-force? ?--? source target

file copy ?-force? ?--? source ?source ...? targetDir
The first form makes a copy of the file or directory source under the pathname target. If target
is an existing directory, then the second form is used. The second form makes a copy inside
targetDir of each source file listed. If a directory is specified as a source, then the contents
of the directory will be recursively copied into targetDir. Existing files will not be overwritten
unless the -force option is specified. When copying within a single filesystem, file copy will
copy soft links (i.e. the links themselves are copied, not the things they point to). Trying to
overwrite a non-empty directory, overwrite a directory with a file, or overwrite a file with a
directory will all result in errors even if -force was specified. Arguments are processed in the
order specified, halting at the first error, if any. A -- marks the end of switches; the argument
following the -- will be treated as a source even if it starts with a -.

file delete ?-force? ?--? pathname ?pathname ... ?
Removes the file or directory specified by each pathname argument. Non-empty directories will be
removed only if the -force option is specified. When operating on symbolic links, the links
themselves will be deleted, not the objects they point to. Trying to delete a non-existent file
is not considered an error. Trying to delete a read-only file will cause the file to be deleted,
even if the -force flags is not specified. If the -force option is specified on a directory, Tcl
will attempt both to change permissions and move the current directory 'pwd' out of the given path
if that is necessary to allow the deletion to proceed. Arguments are processed in the order
specified, halting at the first error, if any. A -- marks the end of switches; the argument
following the -- will be treated as a pathname even if it starts with a -.

file dirname name
Returns a name comprised of all of the path components in name excluding the last element. If
name is a relative file name and only contains one path element, then returns ``.''. If name
refers to a root directory, then the root directory is returned. For example,
file dirname c:/
returns c:/.

Note that tilde substitution will only be performed if it is necessary to complete the command.
For example,
file dirname ~/src/foo.c
returns ~/src, whereas
file dirname ~
returns /home (or something similar).

file executable name
Returns 1 if file name is executable by the current user, 0 otherwise.

file exists name
Returns 1 if file name exists and the current user has search privileges for the directories
leading to it, 0 otherwise.

file extension name
Returns all of the characters in name after and including the last dot in the last element of
name. If there is no dot in the last element of name then returns the empty string.

file isdirectory name
Returns 1 if file name is a directory, 0 otherwise.

file isfile name
Returns 1 if file name is a regular file, 0 otherwise.

file join name ?name ...?
Takes one or more file names and combines them, using the correct path separator for the current
platform. If a particular name is relative, then it will be joined to the previous file name
argument. Otherwise, any earlier arguments will be discarded, and joining will proceed from the
current argument. For example,
file join a b /foo bar
returns /foo/bar.

Note that any of the names can contain separators, and that the result is always canonical for the
current platform: / for Unix and Windows.

file link ?-linktype? linkName ?target?
If only one argument is given, that argument is assumed to be linkName, and this command returns
the value of the link given by linkName (i.e. the name of the file it points to). If linkName
isn't a link or its value cannot be read (as, for example, seems to be the case with hard links,
which look just like ordinary files), then an error is returned. If 2 arguments are given, then
these are assumed to be linkName and target. If linkName already exists, or if target doesn't
exist, an error will be returned. Otherwise, Tcl creates a new link called linkName which points
to the existing filesystem object at target, where the type of the link is platform-specific (on
Unix a symbolic link will be the default). This is useful for the case where the user wishes to
create a link in a cross-platform way, and doesn't care what type of link is created. If the user
wishes to make a link of a specific type only, (and signal an error if for some reason that is not
possible), then the optional -linktype argument should be given. Accepted values for -linktype
are "-symbolic" and "-hard". When creating links on filesystems that either do not support any
links, or do not support the specific type requested, an error message will be returned. In
particular Windows 95, 98 and ME do not support any links at present, but most Unix platforms
support both symbolic and hard links (the latter for files only), MacOS supports symbolic links
and Windows NT/2000/XP (on NTFS drives) support symbolic directory links and hard file links.

file lstat name varName
Same as stat option (see below) except uses the lstat kernel call instead of stat. This means
that if name refers to a symbolic link the information returned in varName is for the link rather
than the file it refers to. On systems that don't support symbolic links this option behaves
exactly the same as the stat option.

file mkdir dir ?dir ...?
Creates each directory specified. For each pathname dir specified, this command will create all
non-existing parent directories as well as dir itself. If an existing directory is specified,
then no action is taken and no error is returned. Trying to overwrite an existing file with a
directory will result in an error. Arguments are processed in the order specified, halting at the
first error, if any.

file mtime name ?time?
Returns a decimal string giving the time at which file name was last modified. If time is
specified, it is a modification time to set for the file (equivalent to Unix touch). The time is
measured in the standard POSIX fashion as seconds from a fixed starting time (often January 1,
1970). If the file doesn't exist or its modified time cannot be queried or set then an error is
generated.

file nativename name
Returns the platform-specific name of the file. This is useful if the filename is needed to pass
to a platform-specific call, such as exec under Windows.

file normalize name
Returns a unique normalized path representation for the file-system object (file, directory, link,
etc), whose string value can be used as a unique identifier for it. A normalized path is an
absolute path which has all '../', './' removed. Also it is one which is in the ``standard''
format for the native platform. On MacOS, Unix, this means the segments leading up to the path
must be free of symbolic links/aliases (but the very last path component may be a symbolic link),
and on Windows it also means we want the long form with that form's case-dependence (which gives
us a unique, case-dependent path). The one exception concerning the last link in the path is
necessary, because Tcl or the user may wish to operate on the actual symbolic link itself (for
example 'file delete', 'file rename', 'file copy' are defined to operate on symbolic links, not on
the things that they point to).

file owned name
Returns 1 if file name is owned by the current user, 0 otherwise.

file pathtype name
Returns one of absolute, relative, volumerelative. If name refers to a specific file on a
specific volume, the path type will be absolute. If name refers to a file relative to the current
working directory, then the path type will be relative. If name refers to a file relative to the
current working directory on a specified volume, or to a specific file on the current working
volume, then the path type is volumerelative.

file readable name
Returns 1 if file name is readable by the current user, 0 otherwise.

file readlink name
Returns the value of the symbolic link given by name (i.e. the name of the file it points to). If
name isn't a symbolic link or its value cannot be read, then an error is returned. On systems
that don't support symbolic links this option is undefined.

file rename ?-force? ?--? source target

file rename ?-force? ?--? source ?source ...? targetDir
The first form takes the file or directory specified by pathname source and renames it to target,
moving the file if the pathname target specifies a name in a different directory. If target is an
existing directory, then the second form is used. The second form moves each source file or
directory into the directory targetDir. Existing files will not be overwritten unless the -force
option is specified. When operating inside a single filesystem, Tcl will rename symbolic links
rather than the things that they point to. Trying to overwrite a non-empty directory, overwrite a
directory with a file, or a file with a directory will all result in errors. Arguments are
processed in the order specified, halting at the first error, if any. A -- marks the end of
switches; the argument following the -- will be treated as a source even if it starts with a -.

file rootname name
Returns all of the characters in name up to but not including the last ``.'' character in the last
component of name. If the last component of name doesn't contain a dot, then returns name.

file separator ?name?
If no argument is given, returns the character which is used to separate path segments for native
files on this platform. If a path is given, the filesystem responsible for that path is asked to
return its separator character. If no file system accepts name, an error is generated.

file size name
Returns a decimal string giving the size of file name in bytes. If the file doesn't exist or its
size cannot be queried then an error is generated.

file split name
Returns a list whose elements are the path components in name. The first element of the list will
have the same path type as name. All other elements will be relative. Path separators will be
discarded unless they are needed ensure that an element is unambiguously relative. For example,
under Unix
file split /foo/~bar/baz
returns / foo ./~bar baz to ensure that later commands that use the third component do not
attempt to perform tilde substitution.

file stat name varName
Invokes the stat kernel call on name, and uses the variable given by varName to hold information
returned from the kernel call. VarName is treated as an array variable, and the following
elements of that variable are set: atime, ctime, dev, gid, ino, mode, mtime, nlink, size, type,
uid. Each element except type is a decimal string with the value of the corresponding field from
the stat return structure; see the manual entry for stat for details on the meanings of the
values. The type element gives the type of the file in the same form returned by the command file
type. This command returns an empty string.

file system name
Returns a list of two elements, the first of which is the name of the filesystem to use for the
file, and the second an arbitrary string representing the filesystem-specific nature or type of
the location within that filesystem. If a filesystem only supports one type of file, the second
element may be null. For example the native files have a first element 'native', and a second
element which is a platform-specific type name for the file's system (e.g. 'NTFS', 'FAT', etc), or
possibly the empty string if no further information is available or if this is not implemented. A
generic virtual file system might return the list 'vfs ftp' to represent a file on a remote ftp
site mounted as a virtual filesystem through an extension called 'vfs'. If the file does not
belong to any filesystem, an error is generated.

file tail name
Returns all of the characters in name after the last directory separator. If name contains no
separators then returns name.

file type name
Returns a string giving the type of file name, which will be one of file, directory,
characterSpecial, blockSpecial, fifo, link, or socket.

file volumes
Returns the absolute paths to the volumes mounted on the system, as a proper Tcl list. On UNIX,
the command will always return "/", since all filesystems are locally mounted. On Windows, it
will return a list of the available local drives (e.g. {a:/ c:/}).

file writable name
Returns 1 if file name is writable by the current user, 0 otherwise.

PORTABILITY ISSUES

       Unix
              These commands always operate using the real user and group identifiers, not the effective ones.

EXAMPLES

       This  procedure  shows  how  to search for C files in a given directory that have a correspondingly-named
       object file in the current directory:
              proc findMatchingCFiles {dir} {
                 set files {}
                 switch $::tcl_platform(platform) {
                    windows {
                       set ext .obj
                    }
                    unix {
                       set ext .o
                    }
                 }
                 foreach file [glob -nocomplain -directory $dir *.c] {
                    set objectFile [file tail [file rootname $file]]$ext
                    if {[file exists $objectFile]} {
                       lappend files $file
                    }
                 }
                 return $files
              }

       Rename a file and leave a symbolic link pointing from the old location to the new place:
              set oldName foobar.txt
              set newName foo/bar.txt
              # Make sure that where we're going to move to exists...
              if {![file isdirectory [file dirname $newName]]} {
                 file mkdir [file dirname $newName]
              }
              file rename $oldName $newName
              file link -symbolic $oldName $newName

KEYWORDS