popen function

popen is used to read and write to a unix pipe.

This function is NOT included in 'C Programming Language' (ANSI) but can be found in 'The Standard C Library' book.


   Library:   stdio.h

   Prototype: FILE *popen(const char *command, const char *type);

   Syntax:    FILE *fp;
	      fp = popen( "ls -l", "r");

   Notes:
	   command - is the command to be issued.
	   type    - r - read O/P from command.
                   - w - Write data as I/P to command.

Examples:

example program.

Notes:

popen will always execute the command from within the Bourne shell.
popen feeds the STDOUT back to your program. If you want STDERR, the following will do the trick.
```
	fp=popen("ls -l 2>&1", "w");
		        AAAA
		        ||||
```

See Also:

fgetc Get a character from a file.
fputc Put a character into a file.man pages
fprintf Put a formatted line into a file.
fopen Open a file.
fclose Close a file.
pclose Close a pipe.
system Open a pipe.