3.2.165 sysopen

sysopen 

FILEHANDLE

, 

FILENAME

, 

MODE

 sysopen 

FILEHANDLE

, 

FILENAME

, 

MODE

, 

PERMS

This function opens the file whose filename is given by FILENAME , and associates it with FILEHANDLE . If FILEHANDLE is an expression, its value is used as the name of (or reference to) the filehandle. This function calls open (2) with the parameters FILENAME , MODE , PERMS .

The possible values and flag bits of the MODE parameter are system-dependent; they are available via the Fcntl library module. However, for historical reasons, some values are universal: zero means read-only, one means write-only, and two means read/write.

If the file named by FILENAME does not exist and sysopen creates it (typically because MODE includes the O_CREAT flag), then the value of PERMS specifies the permissions of the newly created file. If PERMS is omitted, the default value is 0666 , which allows read and write for all. This default is reasonable: see umask .

The FileHandle module described in Chapter 7 provides a more object-oriented approach to sysopen . See also open earlier in this chapter.