CRTL, open, Description
*Conan The Librarian
If a version of the file exists, a new file created with open inherits certain attributes from the existing file unless those attributes are specified in the open call. The following attributes are inherited: record format, maximum record size, carriage control, and file protection. NOTES o If you intend to do random writing to a file, the file must be opened for update by specifying a flags value of O_RDWR. o To create files with OpenVMS RMS default protections by using the UNIX system-call functions umask, mkdir, creat, and open, call mkdir, creat, and open with a file-protection mode argument of 0777 in a program that never specifically calls umask. These default protections include correctly establishing protections based on ACLs, previous versions of files, and so on. In programs that do vfork/exec calls, the new process image inherits whether umask has ever been called or not from the calling process image. The umask setting and whether the umask function has ever been called are both inherited attributes. See also creat, read, write, close, dup, dup2, and lseek.