Watcom C Library Reference : chdir, chmod, chsize
chdir
Synopsis : #include <sys\types.h>
#include <direct.h>
int chdir( const char *path );
Description : The chdir function changes the current working directory to the specified path. The path
can be either relative to the current working directory or it can be an absolute path name.
Returns : The chdir function returns zero if successful. Otherwise, -1 is returned. errno is set to indicate the error, and the current working directory remains unchanged.
Errors : When an error has occurred, errno contains a value indicating the type of error that has been detected.
Constant Meaning
ENOENT The specified path does not exist or path is an empty string.
See Also : getcwd, mkdir, rmdir
Example :
#include <stdio.h>
#include <stdlib.h>
#include <direct.h>
void main( int argc, char *argv[ ] )
{
if( argc != 2 ) {
fprintf( stderr, "Use: cd <directory>\n" );
exit ( 1 );
}
if( chdir( argv[1] ) == 0 ) {
printf( "Directory changed to %s\n", argv[1] );
exit(0);
} else {
perror( argv[1] );
exit ( 1 );
}
}
Classification : POSIX 1003.1
Systems : All
chmod
Synopsis : #include <sys\types.h>
#include <sys\stat.h>
#include <io.h>
int chmod ( const char *path, int permission );
Description : The chmod function changes the permissions for a file specified by path to be the settings in the mode given by permission. The access permissions for the file or directory are specified as a combination of bits (defined in the <sys\stat.h> header file).
The following bits define permissions for the owner.
| Permission | Meaning |
| S_IRWXU | Read, write, execute/search |
| S_IRUSR | Read permission |
| S_IWUSR | Write permission |
| S_IXUSR | Execute/search permission |
The following bits define permissions for the group.
| Permission | Meaning |
| S_IRWXG | Read, write, execute/search |
| S_IRGRP | Read permission |
| S_IWGRP | Write permission |
| S_IXGRP | Execute/search permission |
The following bits define permissions for others.
| Permission | Meaning |
| S_IRWXO | Read, write, execute/search |
| S_IROTH | Read permission |
| S_IWOTH | Write permission |
| S_IXOTH | Execute/search permission |
The following bits define miscellaneous permissions used by other implementations.
| Permission | Meaning |
| S_IREAD | is equivalent to S_IRUSR (read permission) |
| S_IWRITE | is equivalent to S_IWUSR (write permission) |
| S_IEXEC | is equivalent to S_IXUSR (execute/search permission) |
The following bits may also be specified in permission.
| Permission | Meaning |
| S_ISUID | set user id on execution |
| S_ISGID | set group id on execution |
If the calling process does not have appropriate privileges, and if the group ID of does not match the effective group ID or one of the supplementary group IDs, all is a regular file, bit S_ISGID (set group ID on execution) in the file's mode shall be cleared upon successful return from the chmod function.
Upon successful completion, the chmod function will mark for update the st_ctime field of the file.
Returns : The chmod returns zero if the new settings are successfully made; otherwise, -1 is returned and errno is set to indicate the error.
Errors : When an error has occurred, errno contains a value indicating the type of error that has been detected.
| Constant | Meaning |
| EACCES | Search permission is denied for a component of path. |
| ENOENT | The specified path does not exist or path is an empty string. |
See Also : fstat, open, sopen, stat
Example :
/* change the permissions of a list of files to be read/write by the owner only */
#include <stdio.h>
#include <stdlib.h>
#include <sys\types.h>
#include <sys\stat.h>
#include <io.h>
void main( int argc, char *argv[ ] )
{
int i;
int ecode = 0;
for ( i = 1; i < argc; i++ ) {
if ( chmod ( argv[i], S_IRUSR | S_IWUSR ) == -1 ) {
perror( argv[i] );
ecode++;
}
}
exit( ecode );
}
Classification : POSIX 1003.1
Systems : All
chsize
Synopsis : #include <io.h>
int chsize( int handle, long size );
Description : The chsize function changes the size of the file associated with handle by extending or truncating the file to the length specified by size. If the file needs to be extended, the file is padded with NULL ('\0') characters.
Returns : The chsize function returns zero if successful. A return value of -1 indicates an error, ar errno is set to indicate the error.
Errors : When an error has occurred, errno contains a value indicating the type of error that has been detected.
| Constant | Meaning |
| EBADF | Invalid file handle. |
| ENOSPC | Not enough space left on the device to extend the file. |
See Also : close, creat, open
Example :
#include <stdio.h>
#include <io.h>
#include <fcntl.h>
#include <sys\stat.h>
void main( )
{
int handle;
handle = open( "file", O_RDWR | O_CREAT, S_IRUSR | S_IWUSR | S_IRGRP | S_IWGRP );
if( handle != -1 ) {
if( chsize ( handle, 32 * 1024L ) != 0 ) {
printf( "Error extending file\n" );
}
close( handle );
}
}
Classification : WATCOM
Systems : All
This manual describes the WATCOM C library for DOS, Windows, and OS/2, It includes the Standard C Library (as defined in the ANSI C Standard).
WATCOM C Language Reference manual describes the ANSI C Programming language and extensions to it which are supported by WATCOM C/C++ (32bit)
