.TH EXECVE 2
.UC 4
.SH NAME
execve \- execute program
.SH SYNOPSIS
.nf
.B #include <unistd.h>
.B "int execve (const char *filename, const char *argv[], "
.ti 20
.B "const char *envp[]);"
.fi
.SH DESCRIPTION
.B execve()
executes the program pointed to by 
.I filename.
.I filename 
must be either a binary executable, or a shell script starting with the magic 
number #!.  
.B execve()
does not return on success, and the text, data, bss,
and stack of the calling process are overwritten by 
that of the program loaded.
The program invoked inherits the calling process's PID, and any open file 
descriptors that are not set to close on exec.
Signals pending on the parent process are cleared.
On error, a negative number is returned.  
.PP
If the current program is being ptraced, a 
.B SIGTRAP 
is sent to it after a successful 
.B execve().
.SH ERRORS
.B  -EACCESS
is returned when the permissions do not allow the file to be executed.
.PP
.B -ENOENT
is returned when the file does not exist.
.PP
.B -ENOEXEC
is returned when a bad magic number is found or
a shell cannot be found for a #! executable.
.PP
.B -ENOMEM 
is returned when there is insufficient memory to 
.B exec().
.SH FILES
linux/fs/exec.c
.br
linux/kernel/sys_call.s
.br
/usr/include/linux/sys.h
.br
/usr/include/unistd.h
.br
/bin/sh, and user specified shells.
.SH SEE ALSO
execl(3), fork(2)
.SH BUGS
suid and sgid processes can not be 
.B ptrace()'d 
suid or sgid.
.PP
A maximum line length of 127 characters is allowed for the first line
in a #! executable shell script.
This may be circumvented by changing the max size of buf,
in which case you will become bound by the 1024 byte 
size of a buffer, which is not easily worked around.