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<h1>popen function</h1>
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<p>
<b>popen</b> is used to read and write to a unix pipe.<p> This function is NOT
included in 'C Programming Language' (ANSI) but can be found in 'The Standard
C Library' book.
<pre>
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.
</pre>
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<h2>Examples:</h2>
<img src=../../GRAPHICS/computer.gif></a>
<a href=../EXAMPLES/popen.c> example program.</a><p>
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<h2>Notes:</h2>
<ul>
<li>popen will always execute the command from within the Bourne shell.
<li>popen feeds the STDOUT back to your program. If you want STDERR,
the following will do the trick.
<pre>
fp=popen("ls -l 2>&1", "w");
AAAA
||||
</pre>
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<h2>See Also:</h2>
<ul>
<li><a href=fgetc.html>fgetc</a> Get a character from a file.
<li><a href=files.html>fputc</a> Put a character into a file.<i>man pages</i>
<li><a href=fprintf.html>fprintf</a> Put a formatted line into a file.
<li><a href=fopen.html>fopen</a> Open a file.
<li><a href=fclose.html>fclose</a> Close a file.
<li><a href=pclose.html>pclose</a> Close a pipe.
<li><a href=system.html>system</a> Open a pipe.
</ul>
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<address>Martin Leslie
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