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<H1>system_nosh</H1>
Section: Linux Programmer's Manual (3)<BR>Updated: 2014-05-27<BR><A HREF="#index">Index</A>
<A HREF="/#/man/index">Return to Main Contents</A><HR>

<A NAME="lbAB">&nbsp;</A>
<H2>NAME</H2>

<P>
system_nosh, system_execs - execute a command with its arguments from a string without using a shell
<A NAME="lbAC">&nbsp;</A>
<H2>SYNOPSIS</H2>

<B>#include &lt;<A HREF="file:///usr/include/stdlib.h">stdlib.h</A>&gt;</B>

<BR>

<B>#include &lt;<A HREF="file:///usr/include/execs.h">execs.h</A>&gt;</B>

<P>
<B>int system_nosh(const char *</B><I>command</I><B>);</B>

<BR>

<B>int system_execsp(const char *</B><I>command</I><B>);</B>

<P>
<B>int system_execsa(const char *</B><I>command</I><B>);</B>

<BR>

<B>int system_execs(const char *</B><I>path</I><B>, char const *</B><I>command</I><B>);</B>

<P>
<B>int system_execsrp(const char *</B><I>command</I><B>, int </B><I>redir</I><B>[3]);</B>

<P>
<B>int system_execsra(const char *</B><I>command</I><B>, int </B><I>redir</I><B>[3]);</B>

<BR>

<B>int system_execsr(const char *</B><I>path</I><B>, char const *</B><I>command</I><B>, int </B><I>redir</I><B>[3]);</B>

<P>
These functions are provided by libexecs. Link with <I>-lexecs</I>.
<A NAME="lbAD">&nbsp;</A>
<H2>DESCRIPTION</H2>

<B>system_nosh</B> is an almost drop in replacement for <B><A HREF="/#/man/man3/system.3.html">system</A></B>(3)
provided by the libc. <B>system_nosh</B> parses the command string
and runs the command directly, without using a shell.
(<B>system_execsp</B> and <B>system_nosh</B> are synonyms).
<BR>

Command arguments in <I>args</I> are delimited by space characters (blank, tabs
or new lines).
Single or double quotes can be used to delimitate command arguments including
spaces and a non quoted backslash (<B>\</B>)
is the escape character to protect the next char. The executable file
is sought using the PATH environment variable as explained for <B><A HREF="/#/man/man3/execlp.3.html">execlp</A></B>(3).
<BR>

<B>system_execs</B> requires the path of the executable to be specified
as its first parameter so it does not use the PATH environment variable.
<BR>

<B>system_execsa</B> does not use the PATH variable, argv[0] must be
specified as a full pathname.
<BR>

<B>system_execsrp</B> and <B>system_execsr</B> works as their couterparts
without the 'r', but they permit the redirection of standard input, output
and error streams. Their last parameter is an array of three integers.
The standard input of the command will be redirected to <B>redir[0]</B> 
if it is positive, the standard output to <B>redir[1]</B> if it is not
negative and different from 1, the standard error to <B>redir[2]</B> if 
it is not negative and different from 2.
<BR>

<B>system_execsra</B> does not use the PATH variable, argv[0] must be
specified as a full pathname.
<BR>

All these functions can run sequences of commands separated by semicolons (<B>;</B>).
The first command returning a non-zero exit status breaks the sequence.
<A NAME="lbAE">&nbsp;</A>
<H2>RETURN VALUE</H2>

These functions have the same return values of <B><A HREF="/#/man/man3/system.3.html">system</A></B>(3). When
running a sequence of commands, it returns the exit status of the first
command returning a non-zero value. If the return value is zero it means
that all the commands of the sequence succeeded.
<A NAME="lbAF">&nbsp;</A>
<H2>EXAMPLE</H2>

The following program shows the usage of <B>system_nosh</B>:

<P>

<PRE>
#include &lt;<A HREF="file:///usr/include/stdio.h">stdio.h</A>&gt;
#include &lt;<A HREF="file:///usr/include/unistd.h">unistd.h</A>&gt;
#include &lt;<A HREF="file:///usr/include/execs.h">execs.h</A>&gt;

#define BUFLEN 1024
int main(int argc, char *argv)
{
        char buf[BUFLEN];
        printf(&quot;type in a command and its arguments, e.g. 'ls -l'\n&quot;);
        while (fgets(buf, BUFLEN, stdin) != NULL) {
                printf(&quot;Command: '%s' \n&quot;,buf);
                system_nosh(buf);
                printf(&quot;Command done\n&quot;);
        }
}
</PRE>

<A NAME="lbAG">&nbsp;</A>
<H2>SEE ALSO</H2>

<B><A HREF="/#/man/man3/system.3.html">system</A></B>(3),<B><A HREF="/#/man/man3/execs.3.html">execs</A></B>(3),<B><A HREF="/#/man/man3/s2argv.3.html">s2argv</A></B>(3)

<A NAME="lbAH">&nbsp;</A>
<H2>BUGS</H2>

Bug reports should be addressed to &lt;<A HREF="mailto:info@virtualsquare.org">info@virtualsquare.org</A>&gt;
<A NAME="lbAI">&nbsp;</A>
<H2>AUTHOR</H2>

Renzo Davoli &lt;<A HREF="mailto:renzo@cs.unibo.it">renzo@cs.unibo.it</A>&gt;
<P>
<P>

<HR>
<A NAME="index">&nbsp;</A><H2>Index</H2>
<DL>
<DT><A HREF="#lbAB">NAME</A><DD>
<DT><A HREF="#lbAC">SYNOPSIS</A><DD>
<DT><A HREF="#lbAD">DESCRIPTION</A><DD>
<DT><A HREF="#lbAE">RETURN VALUE</A><DD>
<DT><A HREF="#lbAF">EXAMPLE</A><DD>
<DT><A HREF="#lbAG">SEE ALSO</A><DD>
<DT><A HREF="#lbAH">BUGS</A><DD>
<DT><A HREF="#lbAI">AUTHOR</A><DD>
</DL>
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