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filefuncs(3am) - phpMan
FILEFUNCS(3am) GNU Awk Extension Modules FILEFUNCS(3am)
NAME
filefuncs - provide some file related functionality to gawk
SYNOPSIS
@load "filefuncs"
result = chdir("/some/directory")
result = stat("/some/path", statdata [, follow])
flags = or(FTS_PHYSICAL, ...)
result = fts(pathlist, flags, filedata)
DESCRIPTION
The filefuncs extension adds several functions that provide access to file-related facili‐
ties.
chdir()
The chdir() function is a direct hook to the chdir(2) system call to change the current
directory. It returns zero upon success or less than zero upon error. In the latter case
it updates ERRNO.
stat()
The stat() function provides a hook into the stat(2) system call. It returns zero upon
success or less than zero upon error. In the latter case it updates ERRNO. By default,
it uses lstat(2). However, if passed a third argument, it uses stat(2), instead.
In all cases, it clears the statdata array. When the call is successful, stat() fills the
statdata array with information retrieved from the filesystem, as follows:
statdata["name"]
The name of the file.
statdata["dev"]
Corresponds to the st_dev field in the struct stat.
statdata["ino"]
Corresponds to the st_ino field in the struct stat.
statdata["mode"]
Corresponds to the st_mode field in the struct stat.
statdata["nlink"]
Corresponds to the st_nlink field in the struct stat.
statdata["uid"]
Corresponds to the st_uid field in the struct stat.
statdata["gid"]
Corresponds to the st_gid field in the struct stat.
statdata["size"]
Corresponds to the st_size field in the struct stat.
statdata["atime"]
Corresponds to the st_atime field in the struct stat.
statdata["mtime"]
Corresponds to the st_mtime field in the struct stat.
statdata["ctime"]
Corresponds to the st_ctime field in the struct stat.
statdata["rdev"]
Corresponds to the st_rdev field in the struct stat. This element is only present
for device files.
statdata["major"]
Corresponds to the st_major field in the struct stat. This element is only present
for device files.
statdata["minor"]
Corresponds to the st_minor field in the struct stat. This element is only present
for device files.
statdata["blksize"]
Corresponds to the st_blksize field in the struct stat, if this field is present on
your system. (It is present on all modern systems that we know of.)
statdata["pmode"]
A human-readable version of the mode value, such as printed by ls(1). For example,
"-rwxr-xr-x".
statdata["linkval"]
If the named file is a symbolic link, this element will exist and its value is the
value of the symbolic link (where the symbolic link points to).
statdata["type"]
The type of the file as a string. One of "file", "blockdev", "chardev", "direc‐
tory", "socket", "fifo", "symlink", "door", or "unknown". Not all systems support
all file types.
fts()
The fts() function provides a hook to the fts(3) set of routines for traversing file
heirarchies. Instead of returning data about one file at a time in a stream, it fills in
a multi-dimensional array with data about each file and directory encountered in the
requested heirarchies.
The arguments are as follows:
pathlist
An array of filenames. The element values are used; the index values are ignored.
flags This should be the bitwise OR of one or more of the following predefined flag val‐
ues. At least one of FTS_LOGICAL or FTS_PHYSICAL must be provided; otherwise fts()
returns an error value and sets ERRNO.
FTS_LOGICAL
Do a ``logical'' file traversal, where the information returned for a sym‐
bolic link refers to the linked-to file, and not to the symbolic link
itself. This flag is mutually exclusive with FTS_PHYSICAL.
FTS_PHYSICAL
Do a ``physical'' file traversal, where the information returned for a sym‐
bolic link refers to the symbolic link itself. This flag is mutually exclu‐
sive with FTS_LOGICAL.
FTS_NOCHDIR
As a performance optimization, the fts(3) routines change directory as they
traverse a file heirarchy. This flag disables that optimization.
FTS_COMFOLLOW
Immediatly follow a symbolic link named in pathlist, whether or not FTS_LOG‐
ICAL is set.
FTS_SEEDOT
By default, the fts(3) routines do not return entries for ``.'' and ``..''.
This option causes entries for ``..'' to also be included. (The AWK exten‐
sion always includes an entry for ``.'', see below.)
FTS_XDEV
During a traversal, do not cross onto a different mounted filesystem.
filedata
The filedata array is first cleared. Then, fts() creates an element in filedata
for every element in pathlist. The index is the name of the directory or file
given in pathlist. The element for this index is itself an array. There are two
cases.
The path is a file.
In this case, the array contains two or three elements:
"path" The full path to this file, starting from the ``root'' that was given
in the pathlist array.
"stat" This element is itself an array, containing the same information as
provided by the stat() function described earlier for its statdata
argument. The element may not be present if stat(2) for the file
failed.
"error"
If some kind of error was encountered, the array will also contain an
element named "error", which is a string describing the error.
The path is a directory.
In this case, the array contains one element for each entry in the direc‐
tory. If an entry is a file, that element is as for files, just described.
If the entry is a directory, that element is (recursively), an array
describing the subdirectory. If FTS_SEEDOT was provided in the flags, then
there will also be an element named "..". This element will be an array
containing the data as provided by stat().
In addition, there will be an element whose index is ".". This element is
an array containing the same two or three elements as for a file: "path",
"stat", and "error".
The fts() function returns 0 if there were no errors. Otherwise it returns -1.
NOTES
The AWK fts() extension does not exactly mimic the interface of the fts(3) routines,
choosing instead to provide an interface that is based on associative arrays, which should
be more comfortable to use from an AWK program. This includes the lack of a comparison
function, since gawk already provides powerful array sorting facilities. While an
fts_read()-like interface could have been provided, this felt less natural than simply
creating a multi-dimensional array to represent the file heirarchy and its information.
Nothing prevents AWK code from changing the predefined FTS_xx values, but doing so is may
cause strange results when the changed values are passed to fts().
BUGS
There are many more file-related functions for which AWK interfaces would be desirable.
EXAMPLE
See test/fts.awk in the gawk distribution for an example.
SEE ALSO
GAWK: Effective AWK Programming, fnmatch(3am), fork(3am), inplace(3am), ordchr(3am), read‐
dir(3am), readfile(3am), revoutput(3am), rwarray(3am), time(3am).
chdir(2), fts(3), stat(2).
AUTHOR
Arnold Robbins, arnold AT skeeve.com.
COPYING PERMISSIONS
Copyright © 2012, 2013, Free Software Foundation, Inc.
Permission is granted to make and distribute verbatim copies of this manual page provided
the copyright notice and this permission notice are preserved on all copies.
Permission is granted to copy and distribute modified versions of this manual page under
the conditions for verbatim copying, provided that the entire resulting derived work is
distributed under the terms of a permission notice identical to this one.
Permission is granted to copy and distribute translations of this manual page into another
language, under the above conditions for modified versions, except that this permission
notice may be stated in a translation approved by the Foundation.
Free Software Foundation Jan 15 2013 FILEFUNCS(3am)
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