file(n) Tcl Built-In Commands file(n) ______________________________________________________________________________
NAME
file - Manipulate file names and attributes
SYNOPSIS
file option name ?arg arg ...?
______________________________________________________________________________
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 if possible. For path elements that cannot be mapped to
short names, the long name is retained. 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(n), open(n), close(n), eof(n), gets(n), tell(n), seek(n),
fblocked(n), flush(n)
KEYWORDS
attributes, copy files, delete files, directory, file, move files,
name, rename files, stat, user
Tcl 8.3 file(n)
tcl 8.6.15 - Generated Tue Dec 3 16:50:22 CST 2024