Added man pages.

man/man3/system.3

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+.\"	@(#)system.3	6.1 (Berkeley) 5/15/85
+.\"
+.TH SYSTEM 3 "May 15, 1985"
+.AT 3
+.SH NAME
+system \- issue a shell command
+.SH SYNOPSIS
+.nf
+.ft B
+#include <stdlib.h>
+
+int system(const char *\fIstring\fP)
+.fi
+.SH DESCRIPTION
+.B System
+causes the
+.I string
+to be given to
+.BR  sh (1)
+as input as if the string had been typed as a command
+at a terminal.
+The current process waits until the shell has
+completed, then returns the exit status of the shell.
+.SH "SEE ALSO"
+.BR sh (1),
+.BR popen (3),
+.BR execve (2),
+.BR wait (2).
+.SH DIAGNOSTICS
+Exit status 127 indicates the shell couldn't be executed.