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Newer page: version 4 Last edited on Monday, January 31, 2005 8:49:45 pm by CraigBox
Older page: version 1 Last edited on Tuesday, June 4, 2002 12:24:17 am by perry Revert
@@ -1,161 +1,66 @@
-EXEC  
-!!!EXEC  
-NAME  
-SYNOPSIS  
-DESCRIPTION  
-RETURN VALUE  
-FILES  
-ERRORS  
-SEE ALSO  
-COMPATIBILITY  
-CONFORMING TO  
-----  
 !!NAME 
-  
  
 execl, execlp, execle, execv, execvp - execute a file 
+  
 !!SYNOPSIS 
  
+<pre>  
+#include <uinstd.h>  
  
-__#include __  
+extern char **environ;  
  
+int execl( const char *__''path''__, const char *__''arg''__, ...);  
+int execlp( const char *__''file''__, const char *__''arg''__, ...);  
+int execle( const char *__''path''__, const char *__''arg''__,... , char * const__ ''envp''__~[]);  
+int execv( const char *__''path''__, char *const __''argv''__~[]);  
+int execvp( const char *__''file''__, char *const __''argv''__~[]);  
+</pre>  
  
-__extern char **environ;__  
-  
-  
-__int execl( const char *__''path''__, const char  
-*__''arg''__, ...);  
-int execlp( const char *__''file''__, const char  
-*__''arg''__, ...);  
-int execle( const char *__''path''__, const char  
-*__''arg'' __, ..., char * const__  
-''envp''__[[]);  
-int execv( const char *__''path''__, char *const__  
-''argv''__[[]);  
-int execvp( const char *__''file''__, char *const__  
-''argv''__[[]);__  
 !!DESCRIPTION 
  
+The __exec__ family of functions replaces the current process image with a new process image. The functions described in this manual page are front-ends for the function execve(2). (See the manual page for __execve__ for detailed information about the replacement of the current process.)  
  
-The __exec__ family of functions replaces the current  
-process image with a new process image. The functions  
-described in this manual page are front-ends for the  
-function execve(2). (See the manual page for  
-__execve__ for detailed information about the replacement  
-of the current process .)  
+The initial argument for these functions is the pathname of a file which is to be executed
  
-  
-The initial argument for these functions is the pathname of  
-a file which is to be executed.  
-  
-  
- The ''const char *arg'' and subsequent ellipses in the  
- __execl__, __execlp__, and __execle__ functions can  
- be thought of as ''arg0'', ''arg1'', ..., ''argn''.  
- Together they describe a list of one or more pointers to  
- null-terminated strings that represent the argument list  
- available to the executed program. The first argument, by  
- convention, should point to the file name associated with  
- the file being executed. The list of arguments ''must'' 
+The ''const char *arg'' and subsequent ellipses in the __execl__, __execlp__, and __execle__ functions can be thought of as ''arg0'', ''arg1'', ..., ''argn''. Together they describe a list of one or more pointers to null-terminated strings that represent the argument list available to the executed program. The first argument, by convention, should point to the file name associated with the file being executed. The list of arguments ''must'' 
 be terminated by a __NULL__ pointer. 
  
+The __execv__ and __execvp__ functions provide an array of pointers to null-terminated strings that represent the argument list available to the new program. The first argument, by convention, should point to the file name associated with the file being executed. The array of pointers ''must'' be terminated by a __NULL__ pointer.  
  
-The __execv__ and __execvp__ functions provide an  
-array of pointers to null-terminated strings that represent  
-the argument list available to the new program. The first  
-argument, by convention, should point to the file name  
-associated with the file being executed. The array of  
-pointers ''must'' be terminated by a __NULL__  
-pointer.  
-  
-  
- The __execle__ function also specifies the environment of  
- the executed process by following the __NULL__ pointer  
- that terminates the list of arguments in the parameter list  
- or the pointer to the argv array with an additional  
- parameter. This additional parameter is an array of pointers  
- to null-terminated strings and ''must'' be terminated by  
- a __NULL__ pointer. The other functions take the  
- environment for the new process image from the external  
- variable ''environ'' in the current process.  
-  
+The __execle__ function also specifies the environment of the executed process by following the __NULL__ pointer that terminates the list of arguments in the parameter list or the pointer to the argv array with an additional parameter. This additional parameter is an array of pointers to null-terminated strings and ''must'' be terminated by a __NULL__ pointer. The other functions take the environment for the new process image from the external variable ''environ'' in the current process. 
  
 Some of these functions have special semantics. 
  
+The functions __execlp__ and __execvp__ will duplicate the actions of the shell in searching for an executable file if the specified file name does not contain a slash (/) character. The search path is the path specified in the environment by the __PATH__ variable. If this variable isn't specified, the default path ``:/bin:/usr/bin'' is used. In addition, certain errors are treated specially.  
  
-The functions __execlp__ and __execvp __ will duplicate  
- the actions of the shell in searching for an executable file  
-if the specified file name does not contain a slash (/)  
-character. The search path is the path specified in the  
-environment by the __PATH __ variable. If this variable  
-isn't specified, the default path ``:/bin:/usr/bin'' is  
-used. In addition, certain errors are treated  
-specially
+If permission is denied for a file (the attempted __execve __ returned [EACCES]), these functions will continue searching the rest of the search path. If no other file is found, however, they will return with the global variable ''errno'' set to __EACCES __. 
  
+If the header of a file isn't recognized (the attempted __execve__ returned [ENOEXEC]), these functions will execute the shell with the path of the file as its first argument. (If this attempt fails, no further searching is done.)  
  
-If permission is denied for a file (the attempted  
-__execve__ returned __EACCES__), these functions will  
-continue searching the rest of the search path. If no other  
-file is found, however, they will return with the global  
-variable ''errno'' set to __EACCES__.  
-  
-  
-If the header of a file isn't recognized (the attempted  
-__execve__ returned __ENOEXEC__), these functions will  
-execute the shell with the path of the file as its first  
-argument. (If this attempt fails, no further searching is  
-done.)  
 !!RETURN VALUE 
  
+If any of the __exec__ functions returns, an error will have occurred. The return value is -1, and the global variable ''errno'' will be set to indicate the error.  
  
-If any of the __exec__ functions returns, an error will  
-have occurred. The return value is -1, and the global  
-variable ''errno'' will be set to indicate the  
-error.  
 !!FILES 
-  
  
 ''/bin/sh'' 
+  
 !!ERRORS 
  
+All of these functions may fail and set ''errno'' for any of the errors specified for the library function execve(2).  
  
-All of these functions may fail and set ''errno'' for any  
-of the errors specified for the library function  
-execve(2).  
 !!SEE ALSO 
  
+sh(1), execve(2), fork(2), environ(5), ptrace(2)  
  
-sh(1), execve(2), fork(2),  
-environ(5), ptrace(2)  
 !!COMPATIBILITY 
  
+On some other systems the default path (used when the environment does not contain the variable __PATH__) has the current working directory listed after ''/bin'' and ''/usr/bin'', as an anti-Trojan-horse measure. Linux uses here the traditional "current directory first" default path.  
  
-On some other systems the default path (used when the  
-environment does not contain the variable __PATH __) has  
- the current working directory listed after ''/bin'' and  
-''/usr/bin'', as an anti-Trojan-horse measure . Linux uses  
-here the traditional  
-''  
+The behavior of __execlp __ and __execvp__ when errors occur while attempting to execute the file is historic practice, but has not traditionally been documented and is not specified by the [POSIX] standard. [BSD] ( and possibly other systems) do an automatic sleep and retry if [ETXTBSY] is encountered . Linux treats it as a hard error and returns immediately.  
  
+Traditionally, the functions __execlp__ and __execvp__ ignored all errors except for the ones described above and [ENOMEM] and [E2BIG], upon which they returned. They now return if any error other than the ones described above occurs.  
  
-The behavior of __execlp__ and __execvp__ when errors  
-occur while attempting to execute the file is historic  
-practice, but has not traditionally been documented and is  
-not specified by the POSIX standard. BSD (and possibly other  
-systems) do an automatic sleep and retry if ETXTBSY is  
-encountered. Linux treats it as a hard error and returns  
-immediately.  
-  
-  
-Traditionally, the functions __execlp__ and __execvp__  
-ignored all errors except for the ones described above and  
-__ENOMEM__ and __E2BIG__, upon which they returned.  
-They now return if any error other than the ones described  
-above occurs.  
 !!CONFORMING TO 
  
-  
- __execl__, __execv__, __execle__, __execlp__ and  
- __execvp__ conform to IEEE Std1003.1-88  
- (`` POSIX.1'' ).  
-----  
+__execl__, __execv__, __execle__, __execlp__ and __execvp__ conform to IEEE Std1003.1-88 ([ POSIX] .1). 
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