1 .\" Copyright (c) 1980, 1991, 1993
2 .\" The Regents of the University of California. All rights reserved.
4 .\" Redistribution and use in source and binary forms, with or without
5 .\" modification, are permitted provided that the following conditions
7 .\" 1. Redistributions of source code must retain the above copyright
8 .\" notice, this list of conditions and the following disclaimer.
9 .\" 2. Redistributions in binary form must reproduce the above copyright
10 .\" notice, this list of conditions and the following disclaimer in the
11 .\" documentation and/or other materials provided with the distribution.
12 .\" 3. All advertising materials mentioning features or use of this software
13 .\" must display the following acknowledgement:
14 .\" This product includes software developed by the University of
15 .\" California, Berkeley and its contributors.
16 .\" 4. Neither the name of the University nor the names of its contributors
17 .\" may be used to endorse or promote products derived from this software
18 .\" without specific prior written permission.
20 .\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
21 .\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
22 .\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
23 .\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
24 .\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
25 .\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
26 .\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
27 .\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
28 .\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
29 .\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
32 .\" @(#)execve.2 8.5 (Berkeley) 6/1/94
33 .\" $FreeBSD: src/lib/libc/sys/execve.2,v 1.16.2.10 2001/12/22 01:21:30 jwd Exp $
34 .\" $DragonFly: src/lib/libc/sys/execve.2,v 1.2 2003/06/17 04:26:47 dillon Exp $
47 .Fn execve "const char *path" "char *const argv[]" "char *const envp[]"
50 transforms the calling process into a new process.
51 The new process is constructed from an ordinary file,
52 whose name is pointed to by
55 .Em new process file .
56 This file is either an executable object file,
57 or a file of data for an interpreter.
58 An executable object file consists of an identifying header,
59 followed by pages of data representing the initial program (text)
60 and initialized data pages. Additional pages may be specified
61 by the header to be initialized with zero data; see
66 An interpreter file begins with a line of the form:
68 .Bd -ragged -offset indent -compact
74 When an interpreter file is
82 is specified, it becomes the first argument to the
84 and the name of the originally
86 file becomes the second argument;
87 otherwise, the name of the originally
89 file becomes the first argument. The original arguments are shifted over to
90 become the subsequent arguments.
91 The zeroth argument is set to the specified
96 is a pointer to a null-terminated array of
97 character pointers to null-terminated character strings.
98 These strings construct the argument list to be made available to the new
99 process. At least one argument must be present in
100 the array; by custom, the first element should be
101 the name of the executed program (for example, the last component of
106 is also a pointer to a null-terminated array of
107 character pointers to null-terminated strings.
108 A pointer to this array is normally stored in the global variable
110 These strings pass information to the
111 new process that is not directly an argument to the command (see
114 File descriptors open in the calling process image remain open in
115 the new process image, except for those for which the close-on-exec
120 Descriptors that remain open are unaffected by
123 Signals set to be ignored in the calling process are set to be ignored in
126 Signals which are set to be caught in the calling process image
127 are set to default action in the new process image.
128 Blocked signals remain blocked regardless of changes to the signal action.
129 The signal stack is reset to be undefined (see
131 for more information).
133 If the set-user-ID mode bit of the new process image file is set
136 the effective user ID of the new process image is set to the owner ID
137 of the new process image file.
138 If the set-group-ID mode bit of the new process image file is set,
139 the effective group ID of the new process image is set to the group ID
140 of the new process image file.
141 (The effective group ID is the first element of the group list.)
142 The real user ID, real group ID and
143 other group IDs of the new process image remain the same as the calling
145 After any set-user-ID and set-group-ID processing,
146 the effective user ID is recorded as the saved set-user-ID,
147 and the effective group ID is recorded as the saved set-group-ID.
148 These values may be used in changing the effective IDs later (see
151 The set-ID bits are not honored if the respective file system has the
153 option enabled or if the new process file is an interpreter file. Syscall
154 tracing is disabled if effective IDs are changed.
156 The new process also inherits the following attributes from
159 .Bl -column parent_process_ID -offset indent -compact
160 .It process ID Ta see Xr getpid 2
161 .It parent process ID Ta see Xr getppid 2
162 .It process group ID Ta see Xr getpgrp 2
163 .It access groups Ta see Xr getgroups 2
164 .It working directory Ta see Xr chdir 2
165 .It root directory Ta see Xr chroot 2
166 .It control terminal Ta see Xr termios 4
167 .It resource usages Ta see Xr getrusage 2
168 .It interval timers Ta see Xr getitimer 2
169 .It resource limits Ta see Xr getrlimit 2
170 .It file mode mask Ta see Xr umask 2
171 .It signal mask Ta see Xr sigvec 2 ,
175 When a program is executed as a result of an
177 call, it is entered as follows:
178 .Bd -literal -offset indent
179 main(argc, argv, envp)
186 is the number of elements in
191 points to the array of character pointers
192 to the arguments themselves.
196 function overlays the current process image
197 with a new process image the successful call
198 has no process to return to.
201 does return to the calling process an error has occurred; the
202 return value will be -1 and the global variable
204 is set to indicate the error.
207 will fail and return to the calling process if:
210 A component of the path prefix is not a directory.
211 .It Bq Er ENAMETOOLONG
212 A component of a pathname exceeded 255 characters,
213 or an entire path name exceeded 1023 characters.
214 .It Bq Er ENAMETOOLONG
215 When invoking an interpreted script, the interpreter name
220 The new process file does not exist.
222 Too many symbolic links were encountered in translating the pathname.
224 Search permission is denied for a component of the path prefix.
226 The new process file is not an ordinary file.
228 The new process file mode denies execute permission.
230 The new process file has the appropriate access
231 permission, but has an invalid magic number in its header.
233 The new process file is a pure procedure (shared text)
234 file that is currently open for writing or reading by some process.
236 The new process requires more virtual memory than
237 is allowed by the imposed maximum
240 The number of bytes in the new process' argument list
241 is larger than the system-imposed limit.
242 This limit is specified by the
247 The new process file is not as long as indicated by
248 the size values in its header.
255 to an illegal address.
257 An I/O error occurred while reading from the file system.
262 to a non-super-user, but is executed when
265 is ``root'', then the program has some of the powers
266 of a super-user as well.
281 function call appeared in