echard
asked on
Creating and checking for OS directories...
All
Simple question... Is there a standard C library of functions that I can use to see if a directory/file exists, and if not to create a directory at the OS level in a specified location? I assume that this liubrary would also have a function to remove directories...
I would prefer to not use the system() function call directly...
Thanks in advance...
echard
Simple question... Is there a standard C library of functions that I can use to see if a directory/file exists, and if not to create a directory at the OS level in a specified location? I assume that this liubrary would also have a function to remove directories...
I would prefer to not use the system() function call directly...
Thanks in advance...
echard
ASKER
I am terribly sorry for not specifying the OS.. I am developing this on Solaris platform...
ASKER CERTIFIED SOLUTION
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Solaris also has similar functions. try out the manual pages that i have mentioned and let us know if it works for you..
Nothing has happened on this question in over 10 months. It's time for cleanup!
My recommendation, which I will post in the Cleanup topic area, is to
accept answer by akshayxx [grade B] (missed mkdir/rmdir, should not reproduce whole manpages).
PLEASE DO NOT ACCEPT THIS COMMENT AS AN ANSWER!
jmcg
EE Cleanup Volunteer
My recommendation, which I will post in the Cleanup topic area, is to
accept answer by akshayxx [grade B] (missed mkdir/rmdir, should not reproduce whole manpages).
PLEASE DO NOT ACCEPT THIS COMMENT AS AN ANSWER!
jmcg
EE Cleanup Volunteer
there can be a minor difference between windows and UNIX..
here is a function that is available on linux/Unix for checking the existence of file
(for further information do this "man 2 access")
--------------
#include <unistd.h>
int access(const char *pathname, int mode);
DESCRIPTION
access checks whether the process would be allowed to
read, write or test for existence of the file (or other
file system object) whose name is pathname. If pathname
is a symbolic link permissions of the file referred to by
this symbolic link are tested.
--------------------------
to know how to create the file/directory . look this
man 2 open OR man 2 creat (create without 'e')
---------
NAME
open, creat - open and possibly create a file or device
SYNOPSIS
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
int open(const char *pathname, int flags);
int open(const char *pathname, int flags, mode_t mode);
int creat(const char *pathname, mode_t mode);
DESCRIPTION
The open() system call is used to convert a pathname into
a file descriptor (a small, non-negative integer for use
in subsequent I/O as with read, write, etc.). When the
call is successful, the file descriptor returned will be
the lowest file descriptor not currently open for the pro-
cess. This call creates a new open file, not shared with
any other process. (But shared open files may arise via
the fork(2) system call.) The new file descriptor is set
to remain open across exec functions (see fcntl(2)). The
file offset is set to the beginning of the file.
The parameter flags is one of O_RDONLY, O_WRONLY or O_RDWR
which request opening the file read-only, write-only or
read/write, respectively, bitwise-or'd with zero or more
of the following:
O_CREAT
If the file does not exist it will be created. The
owner (user ID) of the file is set to the effective
user ID of the process. The group ownership (group
ID) is set either to the effective group ID of the
process or to the group ID of the parent directory
(depending on filesystem type and mount options,
and the mode of the parent directory, see, e.g.,
the mount options bsdgroups and sysvgroups of the
ext2 filesystem, as described in mount(8)).
O_EXCL When used with O_CREAT, if the file already exists
it is an error and the open will fail. In this con-
text, a symbolic link exists, regardless of where
its points to. O_EXCL is broken on NFS file sys-
tems, programs which rely on it for performing
locking tasks will contain a race condition. The
solution for performing atomic file locking using a
lockfile is to create a unique file on the same fs
(e.g., incorporating hostname and pid), use link(2)
to make a link to the lockfile. If link() returns
0, the lock is successful. Otherwise, use stat(2)
on the unique file to check if its link count has
increased to 2, in which case the lock is also suc-
cessful.
O_NOCTTY
If pathname refers to a terminal device -- see
tty(4) -- it will not become the process's control-
ling terminal even if the process does not have
one.
O_TRUNC
If the file already exists and is a regular file
and the open mode allows writing (i.e., is O_RDWR
or O_WRONLY) it will be truncated to length 0. If
the file is a FIFO or terminal device file, the
O_TRUNC flag is ignored. Otherwise the effect of
O_TRUNC is unspecified. (On many Linux versions it
will be ignored; on other versions it will return
an error.)
O_APPEND
The file is opened in append mode. Before each
write, the file pointer is positioned at the end of
the file, as if with lseek. O_APPEND may lead to
corrupted files on NFS file systems if more than
one process appends data to a file at once. This
is because NFS does not support appending to a
file, so the client kernel has to simulate it,
which can't be done without a race condition.
O_NONBLOCK or O_NDELAY
When possible, the file is opened in non-blocking
mode. Neither the open nor any subsequent opera-
tions on the file descriptor which is returned will
cause the calling process to wait. For the han-
dling of FIFOs (named pipes), see also fifo(4).
This mode need not have any effect on files other
than FIFOs.
O_SYNC The file is opened for synchronous I/O. Any writes
on the resulting file descriptor will block the
calling process until the data has been physically
written to the underlying hardware. See RESTRIC-
TIONS below, though.
O_NOFOLLOW
If pathname is a symbolic link, then the open
fails. This is a FreeBSD extension, which was
added to Linux in version 2.1.126. Symbolic links
in earlier components of the pathname will still be
followed. The headers from glibc 2.0.100 and later
include a definition of this flag; kernels before
2.1.126 will ignore it if used.
O_DIRECTORY
If pathname is not a directory, cause the open to
fail. This flag is Linux-specific, and was added
in kernel version 2.1.126, to avoid denial-of-ser-
vice problems if opendir(3) is called on a FIFO or
tape device, but should not be used outside of the
implementation of opendir.
O_LARGEFILE
On 32-bit systems that support the Large Files Sys-
tem, allow files whose sizes cannot be represented
in 31 bits to be opened.
Some of these optional flags can be altered using fcntl
after the file has been opened.
The argument mode specifies the permissions to use in case
a new file is created. It is modified by the process's
umask in the usual way: the permissions of the created
file are (mode & ~umask). Note that this mode only
applies to future accesses of the newly created file; the
open call that creates a read-only file may well return a
read/write file descriptor.
The following symbolic constants are provided for mode:
S_IRWXU
00700 user (file owner) has read, write and execute
permission
S_IRUSR (S_IREAD)
00400 user has read permission
S_IWUSR (S_IWRITE)
00200 user has write permission
S_IXUSR (S_IEXEC)
00100 user has execute permission
S_IRWXG
00070 group has read, write and execute permission
S_IRGRP
00040 group has read permission
S_IWGRP
00020 group has write permission
S_IXGRP
00010 group has execute permission
S_IRWXO
00007 others have read, write and execute permis-
sion
S_IROTH
00004 others have read permission
S_IWOTH
00002 others have write permisson
S_IXOTH
00001 others have execute permission
mode should always be specified when O_CREAT is in the
flags, and is ignored otherwise.
creat is equivalent to open with flags equal to
O_CREAT|O_WRONLY|O_TRUNC.
------------------