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file(n) Tcl Built-In Commands file(n)
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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 associ-
ated 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 ver-
sions of Unix supporting file flags, -readonly gives the value
or sets or clears the readonly attribute of the file, i.e. the
user immutable flag uchg to chflags(1).
On Windows, -archive gives the value or sets or clears the ar-
chive 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 cre-
ator type of the file. -hidden gives or sets or clears the hid-
den 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 reg-
istered open channels in this interpreter. If pattern is speci-
fied, 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 direc-
tory, 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 argu-
ment. 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, halt-
ing 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 oth-
erwise.
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 cor-
rect 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 dis-
carded, 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 val-
ues 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 abso-
lute, normalized form before the link is created (and therefore
relative paths are interpreted as relative to the cwd). Fur-
thermore, "~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. In particular Windows 95, 98
and ME do not support any links at present, but most Unix plat-
forms support both symbolic and hard links (the latter for files
only) 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 sym-
bolic link the information returned in varName is for the link
rather than the file it refers to. On systems that do not sup-
port symbolic links this option behaves exactly the same as the
stat option.
file mkdir ?dir ...?
Creates each directory specified. For each pathname dir speci-
fied, this command will create all non-existing parent directo-
ries as well as dir itself. If an existing directory is speci-
fied, 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 plat-
form. 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 con-
cerning 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 other-
wise.
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 cur-
rent 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 other-
wise.
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 sys-
tems that do not support symbolic links this option is unde-
fined.
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 tar-
getDir. 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 speci-
fied, 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 ele-
ment 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 substi-
tution.
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 follow-
ing 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 ele-
ment 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 exten- |
sion) 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 other-
wise.
PORTABILITY ISSUES
Unix
These commands always operate using the real user and group
identifiers, not the effective ones.
Windows
The file owned subcommand currently always reports that the cur-
rent user is the owner of the file, without regard for what the
operating system believes to be true, making an ownership test
useless. This issue (#3613671) may be fixed in a future release
of Tcl.
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 dou-
ble-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)
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