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exec.3: Document execpe() 

This function was added to glibc in version 2.11.
Also various other small rewrites in the page.

Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
This commit is contained in:
Michael Kerrisk 2010-09-25 08:22:31 +02:00
parent 91e1b56b2e
commit c63619503f
1 changed files with 37 additions and 24 deletions
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man3/exec.3
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@ -36,9 +36,9 @@
.\" Modified, 24 Jun 2004, Michael Kerrisk <mtk.manpages@gmail.com> .\" Modified, 24 Jun 2004, Michael Kerrisk <mtk.manpages@gmail.com>
.\" Added note on casting NULL .\" Added note on casting NULL
.\" .\"
.TH EXEC 3 2010-09-23 "GNU" "Linux Programmer's Manual" .TH EXEC 3 2010-09-25 "GNU" "Linux Programmer's Manual"
.SH NAME .SH NAME
execl, execlp, execle, execv, execvp \- execute a file execl, execlp, execle, execv, execvp, execvpe \- execute a file
.SH SYNOPSIS .SH SYNOPSIS
.B #include <unistd.h> .B #include <unistd.h>
.sp .sp
@ -55,6 +55,10 @@ execl, execlp, execle, execv, execvp \- execute a file
.BI "int execv(const char *" path ", char *const " argv "[]);" .BI "int execv(const char *" path ", char *const " argv "[]);"
.br .br
.BI "int execvp(const char *" file ", char *const " argv "[]);" .BI "int execvp(const char *" file ", char *const " argv "[]);"
.br
.BI "int execvpe(const char *" file ", char *const " argv "[],"
.br
.BI " char *const " envp "[]);"
.SH DESCRIPTION .SH DESCRIPTION
The The
.BR exec () .BR exec ()
@ -66,7 +70,7 @@ The functions described in this manual page are front-ends for
.BR execve (2) .BR execve (2)
for further details about the replacement of the current process image.) for further details about the replacement of the current process image.)
.PP .PP
The initial argument for these functions is the pathname of a file which is The initial argument for these functions is the name of a file that is
to be executed. to be executed.
.PP .PP
The The
@ -92,9 +96,10 @@ pointer, and, since these are variadic functions, this pointer must be cast
.IR "(char *) NULL" . .IR "(char *) NULL" .
.PP .PP
The The
.BR execv () .BR execv (),
.BR execvp (),
and and
.BR execvp () .BR execvpe ()
functions provide an array of pointers to null-terminated strings that functions provide an array of pointers to null-terminated strings that
represent the argument list available to the new program. represent the argument list available to the new program.
The first argument, by convention, should point to the filename The first argument, by convention, should point to the filename
@ -105,26 +110,27 @@ be terminated by a NULL pointer.
.PP .PP
The The
.BR execle () .BR execle ()
function also specifies the environment of the executed process by following and
the NULL .BR execvpe ()
pointer that terminates the list of arguments in the argument list or the functions allow the caller to specify the environment of the
pointer to the executed program via the argument
.I argv .IR envp .
array with an additional argument. The
This additional .I envp
argument is an array of pointers to null-terminated strings and argument is an array of pointers to null-terminated strings and
.I must .I must
be terminated by a NULL pointer. be terminated by a NULL pointer.
The other functions take the environment for the new process The other functions take the environment for the new process
image from the external variable image from the external variable
.I environ .I environ
in the current process. in the calling process.
.SS Special semantics for execlp() and execvp() .SS Special semantics for execlp() and execvp()
.PP .PP
The The
.BR execlp () .BR execlp (),
.BR execvp (),
and and
.BR execvp () .BR execvpe ()
functions duplicate the actions of the shell in functions duplicate the actions of the shell in
searching for an executable file searching for an executable file
if the specified filename does not contain a slash (/) character. if the specified filename does not contain a slash (/) character.
@ -139,10 +145,9 @@ the current directory followed by the list of directories returned by
.BR confstr (3) .BR confstr (3)
call typically returns the value "/bin:/usr/bin".) call typically returns the value "/bin:/usr/bin".)
If the specified filename includes a slash character, If the specified filename includes a slash character, then
then
.B PATH .B PATH
is ignored, and file at the specified pathname is executed. is ignored, and the file at the specified pathname is executed.
In addition, certain errors are treated specially. In addition, certain errors are treated specially.
@ -166,21 +171,29 @@ these functions will execute the shell
with the path of the file as its first argument. with the path of the file as its first argument.
(If this attempt fails, no further searching is done.) (If this attempt fails, no further searching is done.)
.SH "RETURN VALUE" .SH "RETURN VALUE"
If any of the The
.BR exec () .BR exec ()
functions returns, an error will have occurred. functions only return if an error has have occurred.
The return value is \-1, and The return value is \-1, and
.I errno .I errno
will be set to indicate the error. is set to indicate the error.
.SH ERRORS .SH ERRORS
All of these functions may fail and set All of these functions may fail and set
.I errno .I errno
for any of the errors specified for the library function for any of the errors specified for
.BR execve (2). .BR execve (2).
.SH
The
.BR execvpe ()
function first appeared in glibc 2.11.
.SH "CONFORMING TO" .SH "CONFORMING TO"
POSIX.1-2001. POSIX.1-2001, POSIX.1-2008.
The
.BR execvpe ()
function is a GNU extension.
.SH NOTES .SH NOTES
On some other systems the default path (used when the environment On some other systems, the default path (used when the environment
does not contain the variable \fBPATH\fR) has the current working does not contain the variable \fBPATH\fR) has the current working
directory listed after directory listed after
.I /bin .I /bin