Provided by: tcl8.6-doc_8.6.14+dfsg-1build1_all 
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 does not 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 options and their values. The second form returns the
value for the given 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 retrieves or sets a file's access permissions, using octal notation by default. This
option also provides limited support for setting permissions using the symbolic notation accepted
by the chmod command, following the form [ugo]?[[+-=][rwxst],[...]]. Multiple permission
specifications may be given, separated by commas. E.g., u+s,go-rw would set the setuid bit for a
file's owner as well as remove read and write permission for the file's group and other users. An
ls-style string of the form rwxrwxrwx is also accepted but must always be 9 characters long. E.g.,
rwxr-xr-t is equivalent to 01755. On versions of Unix supporting file flags, -readonly returns the
value of, or sets, or clears the readonly attribute of a file, i.e., the user immutable flag
(uchg) to the chflags command.
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.
On Mac OS X and Darwin, -creator gives or sets the Finder creator type of the file. -hidden gives
or sets or clears the hidden attribute of the file. -readonly gives or sets or clears the readonly
attribute of the file. -rsrclength gives the length of the resource fork of the file, this
attribute can only be set to the value 0, which results in the resource fork being stripped off
the file.
file channels ?pattern?
If pattern is not specified, returns a list of names of all registered open channels in this
interpreter. If pattern is specified, only those names matching pattern are returned. Matching
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 Tcl will also attempt to adjust permissions on the
destination file or directory if that is necessary to allow the copy to proceed). 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 ... ?
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. On Windows, which does not
have an executable attribute, the command treats all directories and any files with extensions
exe, com, cmd or bat as executable.
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 is
not 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 does not exist, an error will be returned. Otherwise, Tcl creates a new link
called linkName which points to the existing filesystem object at target (which is also the
returned value), 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 does not 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”.
On Unix, symbolic links can be made to relative paths, and those paths must be relative to the
actual linkName's location (not to the cwd), but on all other platforms where relative links are
not supported, target paths will always be converted to absolute, normalized form before the link
is created (and therefore relative paths are interpreted as relative to the cwd). Furthermore,
“~user” paths are always expanded to absolute form. 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. Most Unix platforms support both symbolic and hard links (the latter for files
only). Windows supports symbolic directory links and hard file links on NTFS drives.
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 do not support symbolic links this option behaves
exactly the same as the stat option.
file mkdir ?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 does not 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 to a subprocess via exec under Windows (see EXAMPLES below).
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 “../” and “./” removed. Also it is one which is in the “standard”
format for the native platform. On 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 is not a symbolic link or its value cannot be read, then an error is returned. On systems
that do not 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 does not 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 does not 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 to 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 one or two elements, the first of which is the name of the filesystem to use for
the file, and the second, if given, 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 not be supplied. For example the native files have a first element
“native”, and a second element which when given is a platform-specific type name for the file's
system (e.g. “NTFS”, “FAT”, on Windows). 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 the last filesystem component of name. Any trailing directory
separator in name is ignored. If name contains no separators then returns name. So, file tail
a/b, file tail a/b/ and file tail b all return b.
file tempfile ?nameVar? ?template?
Creates a temporary file and returns a read-write channel opened on that file. If the nameVar is │
given, it specifies a variable that the name of the temporary file will be written into; if │
absent, Tcl will attempt to arrange for the temporary file to be deleted once it is no longer │
required. If the template is present, it specifies parts of the template of the filename to use │
when creating it (such as the directory, base-name or extension) though some platforms may ignore │
some or all of these parts and use a built-in default instead. │
Note that temporary files are only ever created on the native filesystem. As such, they can be │
relied upon to be used with operating-system native APIs and external programs that require a │
filename. │
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. Without
any virtual filesystems mounted as root volumes, 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:/”). If any virtual filesystem has mounted additional volumes, they
will be in the returned list.
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.
Windows
The file owned subcommand uses the user identifier (SID) of the process token, not the thread
token which may be impersonating some other user.
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
On Windows, a file can be “started” easily enough (equivalent to double-clicking on it in the Explorer
interface) but the name passed to the operating system must be in native format:
exec {*}[auto_execok start] {} [file nativename ~/example.txt]
SEE ALSO
filename(3tcl), open(3tcl), close(3tcl), eof(3tcl), gets(3tcl), tell(3tcl), seek(3tcl), fblocked(3tcl),
flush(3tcl)
KEYWORDS
attributes, copy files, delete files, directory, file, move files, name, rename files, stat, user