CODEWITHSUNDEEP
c++fileunixstdout
Jacko
Jacko

Reputation: 13195

Program that writes to /dev/stdout: how to send EOF?

I have a program that writes data to a file. Normally, the file is on disk, but I am experimenting with writing to /dev/stdout. Currently, when I do this, the program will not exit until I press Ctrl-C . Is there a way for the program to signal that the output is done ?

Edit:

Currently, a disk file is opened via fopen(FILE_NAME), so I am now trying to pass in /dev/stdout as FILE_NAME.

Edit 2:

command line is

MY_PROGRAM -i foo -o /dev/stdout > dump.png

Edit 3:

It looks like the problem here is that stdout is already open, and I am opening it a second time.

Upvotes: 1

Views: 2245

Answers (1)

Charles Duffy
Charles Duffy

Reputation: 295649

The EOF condition on a FIFO (which, if you're piping from your program into something else, is what your stdout is) is set when no file handles are still open for write.

In C, the standard-library is fclose(stdout), whereas the syscall interface is close(1) -- if you're using fopen(), you'll want to pair it with fclose().

If you're also doing a separate outFile = fopen("/dev/stdout", "w") or similar, then you'll need to close that copy as well: fclose(outFile) as well as fclose(stdout).

Upvotes: 2

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