廢話很少說，相信你確定也在system接口上填過坑！先上一把它的正確操做：linux

#include

#include

#define Debuging(fmt, arg...) printf(fmt, ##arg)

int new_system(char *cmd, char *resultout, int buflen, int *lenout)

{

int status = system(cmd);

Debuging("cmd=%s\n", cmd);

if (-1 == status)

{

Debuging("system error!\n");

}

else

{

Debuging("exit status value = [0x%x]\n", status);

if (WIFEXITED(status))

{

if (0 == WEXITSTATUS(status))

{

Debuging("run shell script successfully.\n");

return 0;

}

else

{

Debuging("run shell script fail, script exit code: %d\n", WEXITSTATUS(status));

}

}

else

{

Debuging("exit status = [%d]\n", WEXITSTATUS(status));

}

}

return -1;

}

示例代碼中很好地展現了，如何判斷system接口的返回值！shell

如下是linux man中關于system接口的介紹：bash

SYSTEM(3)? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? Linux Programmer's Manual? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? SYSTEM(3)less

NAMEide

system - execute a shell commandoop

SYNOPSISui

#include this

int system(const char *command);code

DESCRIPTIONorm

The? system()? library? function? uses? fork(2) to create a child process that executes the shell command specified in command using

execl(3) as follows:

execl("/bin/sh", "sh", "-c", command, (char *) 0);

system() returns after the command has been completed.

During execution of the command, SIGCHLD will be blocked, and SIGINT and SIGQUIT will be ignored, in the process that calls system()

(these signals will be handled according to their defaults inside the child process that executes command).

If command is NULL, then system() returns a status indicating whether a shell is available on the system

RETURN VALUE

The return value of system() is one of the following:

*? If command is NULL, then a nonzero value if a shell is available, or 0 if no shell is available.

*? If a child process could not be created, or its status could not be retrieved, the return value is -1.

*? If? a? shell could not be executed in the child process, then the return value is as though the child shell terminated by calling

_exit(2) with the status 127.

*? If all system calls succeed, then the return value is the termination status of the child shell used to? execute? command. ? (The

termination status of a shell is the termination status of the last command it executes.)

In? the? last? two cases, the return value is a "wait status" that can be examined using the macros described in waitpid(2).? (i.e.,

WIFEXITED() WEXITSTATUS() and so on).

system() does not affect the wait status of any other children.

ATTRIBUTES

For an explanation of the terms used in this section, see attributes(7).

┌──────────┬───────────────┬─────────┐

│Interface │ Attribute ? ? │ Value ? │

├──────────┼───────────────┼─────────┤

│system()? │ Thread safety │ MT-Safe │

└──────────┴───────────────┴─────────┘

CONFORMING TO

POSIX.1-2001, POSIX.1-2008, C89, C99.

NOTES

system() provides simplicity and convenience: it handles all of the details of calling fork(2), execl(3), and waitpid(2), as well as

the? necessary? manipulations? of signals; in addition, the shell performs the usual substitutions and I/O redirections for command.

The main cost of system() is inefficiency: additional system calls are required to create the process that runs? the? shell? and? to

execute the shell.

If? the? _XOPEN_SOURCE? feature? test? macro is defined (before including any header files), then the macros described in waitpid(2)

(WEXITSTATUS(), etc.) are made available when including .

As mentioned, system() ignores SIGINT and SIGQUIT.? This may make programs that call it from a? loop? uninterruptible,? unless? they

take care themselves to check the exit status of the child.? For example:

while (something) {

int ret = system("foo");

if (WIFSIGNALED(ret) &&

(WTERMSIG(ret) == SIGINT || WTERMSIG(ret) == SIGQUIT))

break;

}

Do? not? use? system() from a program with set-user-ID or set-group-ID privileges, because strange values for some environment vari‐

ables might be used to subvert system integrity.? Use the exec(3) family of functions instead, but not execlp(3) or execvp(3).? sys‐

tem() will not, in fact, work properly from programs with set-user-ID or set-group-ID privileges on systems on which /bin/sh is bash

version 2, since bash 2 drops privileges on startup.? (Debian uses a modified bash which does not do this when invoked as sh.)

In versions of glibc before 2.1.3, the check for the availability of /bin/sh was not actually performed if command was NULL; instead

it? was? always? assumed? to? be available, and system() always returned 1 in this case.? Since glibc 2.1.3, this check is performed

because, even though POSIX.1-2001 requires a conforming implementation to provide a shell, that shell may not be available? or? exe‐

cutable if the calling program has previously called chroot(2) (which is not specified by POSIX.1-2001).

It? is possible for the shell command to terminate with a status of 127, which yields a system() return value that is indistinguish‐

able from the case where a shell could not be executed in the child process.

SEE ALSO

sh(1), sigaction(2), sigprocmask(2), fork(2), wait(2), exec(3), signal(7)

COLOPHON

This page is part of release 4.04 of the Linux man-pages project.? A description of the project, information about? reporting? bugs,

and the latest version of this page, can be found at http://www.kernel.org/doc/man-pages/.

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