4
我可以編譯提供給我的這個程序，但我必須進一步開發。我有一些關於它的問題：如何運行此程序？
#include <sys/types.h>
#include <signal.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <errno.h>
#define TIMEOUT (20)
int main(int argc, char *argv[])
{
pid_t pid;
if(argc > 1 && strncmp(argv[1], "-help", strlen(argv[1])) == 0)
{
fprintf(stderr, "Usage: RunSafe Prog [CommandLineArgs]\n\nRunSafe takes as arguments:\nthe program to be run (Prog) and its command line arguments (CommandLineArgs) (if any)\n\nRunSafe will execute Prog with its command line arguments and\nterminate it and any remaining childprocesses after %d seconds\n", TIMEOUT);
exit(0);
}
if((pid = fork()) == 0) /* Fork off child */
{
execvp(argv[1], argv+1);
fprintf(stderr,"RunSafe failed to execute: %s\n",argv[1]);
perror("Reason");
kill(getppid(),SIGKILL); /* kill waiting parent */
exit(errno); /* execvp failed, no child - exit immediately */
}
else if(pid != -1)
{
sleep(TIMEOUT);
if(kill(0,0) == 0) /* are there processes left? */
{
fprintf(stderr,"\nRunSafe: Attempting to kill remaining (child) processes\n");
kill(0, SIGKILL); /* send SIGKILL to all child processes */
}
}
else
{
fprintf(stderr,"RunSafe failed to fork off child process\n");
perror("Reason");
}
}
當我編譯它時，我的警告是什麼意思？
$ gcc -o RunSafe RunSafe.c -lm
RunSafe.c: In function ‘main’:
RunSafe.c:30:44: warning: incompatible implicit declaration of built-in function ‘strlen’ [enabled by default]
爲什麼我不能執行該文件？
$ file RunSafe
RunSafe: ELF 64-bit LSB executable, x86-64, version 1 (SYSV), dynamically linked (uses shared libs), for GNU/Linux 2.6.24, BuildID[sha1]=0x0a128c8d71e16bfde4dbc316bdc329e4860a195f, not stripped
[email protected]:/media/Lexar$ sudo chmod 777 RunSafe
[email protected]:/media/Lexar$ ./RunSafe
bash: ./RunSafe: Permission denied
[email protected]:/media/Lexar$ sudo ./RunSafe
sudo: ./RunSafe: command not found
添加到@ Greg的響應我相信如果'noexec'選項不是mount選項，'/ media/Lexar'可能是一種不同類型的文件系統，可能是FAT或其他。 – g13n
僅僅通過FAT通常不足以阻止執行。 –
那麼，如果操作系統在FAT上，操作系統將不會運行該程序。儘管chmod將會成功，但可執行位將不會被設置。因此shell會抱怨拒絕許可。 – g13n