file
Manipulate file names and attributes
Syntax
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.
option indicates what to do with the file name.
Any unique abbreviation for option is acceptable. The
valid options are:
- file atime name
- Returns a decimal string giving the time at which file name
was last accessed. 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 then an
error is generated.
- file dirname name
- Returns all of the characters in name up to but not
including the last slash character. If there are no slashes in
name then it returns
.. If the last slash in
name is its first character, then it returns /.
- 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 name. If there is no dot in
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 lstat name varName
- Same as stat option (see below) except this 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 mtime name
- Returns a decimal string giving the time at which file
name was last modified. 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 then an error is generated.
- file owned name
- Returns 1 if file name is owned by
the current user, 0 otherwise.
- 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 rootname name
- Returns all of the characters in name up to but not
including the last
. character in the name. If
name doesn't contain a dot, then it returns name.
- 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 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 tail name
- Returns all of the characters in name after the last
slash. If name contains no slashes then it 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 writable name
- Returns 1 if file name is writable
by the current user, 0 otherwise.