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Read output from system( ).

I need to read the output from a system( ) function within a C program.
The function however only returns the exit status.
How can I read what system( ) sends to stdout ?
(is there a simpler way than having to fork a child process and then
catching its output ?)
(if needed: working on linux)


Nov 13 '05
20 13146
In <bl**********@s parta.btinterne t.com> Richard Heathfield <do******@addre ss.co.uk.invali d> writes:
Dan Pop wrote:
In <bl**********@s parta.btinterne t.com> Richard Heathfield writes:
SR wrote:
I need to read the output from a system( ) function within a C program.
The function however only returns the exit status.
How can I read what system( ) sends to stdout ?

system("fo o > filename.txt");
fp = fopen("filename .txt", r");

Where does the standard say that, if the fopen call succeeds, the
stream contains the output of the command executed by system()?

For a moment I forgot where I was, and I accidentally gave a pragmatic reply
that would actually help the OP out of his current difficulty. I do
apologise - to you, to the OP, and indeed to the whole group. I'll try not
to make the same mistake again.

I am the last one to object to providing helpful answers, as long as they
are accompanied by the mandatory caveats, so that both the OP and any
other newbie who happens to read the answer know that:

1. The solution is platform-specific.

2. Usually, there are better platform-specific solutions (e.g. popen on
Unix systems).

Dan Pop
DESY Zeuthen, RZ group
Email: Da*****@ifh.de
Nov 13 '05 #21

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