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Changing stdin from file redirection to console input


 
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# 1  
Old 09-28-2001
CPU & Memory Changing stdin from file redirection to console input

Hi

I am doing file redirection at console for use by my binary.

%console%> bin &lt inputfile

After reading in the entire file, I want my program to continue taking input from the console. So essentially I want to redirect stdin back to console. But I cant figure out how to do it.

I am using GNU compiler on Linux and Solaris. Can anyone help me in this regard.

Thanx
Nauman

Last edited by nauman; 09-28-2001 at 09:01 PM..
# 2  
Old 09-29-2001
I'm not exactly clear what
you are trying to do but
after your done reading the file,
try closing all fd's

// assuming you have no more that 10 files open
for(i = 0; i < 10; i++)
{
if(close(i) < 0)
break;
}

...then open a new file. The fd will be 0 (stdin).
# 3  
Old 09-29-2001
Question

I am not opening any file in my program. The file is being redirected to stdin by the OS.

bin &lt inputfile

I am using gets() to read, which not to mention read from the stdin. After I am finished reading the file, I want gets() to continue reading from console input.

Are u implying that file redirection causes a fd attached to stdin. If so when I reopen the fd, what argument should I give it, to attach it to console input.

I am going to try it next anyway and see what happens.

Thanx

Nauman
# 4  
Old 09-29-2001
When a program is loaded by the OS,
it is automatically given 3 open files...

stdin -> fd=0
stdout -> fd=1
stderr -> fd=2

By closing all fd's you guarantee that
the next file you open...

open(...)

...will be assigned fd 0
# 5  
Old 09-29-2001
MySQL

Thanx. Ur comments really helped. Besides I also got to know how OS works and how to redirect stdin.

Thanx and regards
Nauman

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