最近在看深入理解計算機系統，看到一個函數叫做execve()，這個函數很有意思，可以在一個進程插入另外一個進程執行，但是又不像fork()一樣產生一個子進程，execve()插入的進程和原進程共享進程號，就好像執行這進程就像執行過程調用一般隨意。
函數原型如下：
int execve(const char *filename, char *const argv[], char *const envp[]);
EXAMPLE
The following program is designed to be execed by the second program below. It just echoes its command-line one per line.
/* myecho.c */
#include <stdio.h>
#include <stdlib.h>
int
main(int argc, char *argv[])
{
int j;
for (j = 0; j < argc; j++)
printf("argv[%d]: %s\n", j, argv[j]);
exit(EXIT_SUCCESS);
}
This program can be used to exec the program named in its command-line argument:
/* execve.c */
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
int
main(int argc, char *argv[])
{
char *newargv[] = { NULL, "hello", "world", NULL };
char *newenviron[] = { NULL };
if (argc != 2) {
fprintf(stderr, "Usage: %s <file-to-exec>\n", argv[0]);
exit(EXIT_FAILURE);
}
newargv[0] = argv[1];
execve(argv[1], newargv, newenviron);
perror("execve"); /* execve() only returns on error */
exit(EXIT_FAILURE);
}
We can use the second program to exec the first as follows:
$ cc myecho.c -o myecho
$ cc execve.c -o execve
$ ./execve ./myecho
argv[0]: ./myecho
argv[1]: hello
argv[2]: world
插入一個shell腳本執行：
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
int
main(int argc, char *argv[])
{
char *newargv[] = { "/etc" };
char *newenviron[] = { NULL };
if (argc != 2)
{
fprintf(stderr, "Usage: %s <file-to-exec>\n", argv[0]);
exit(EXIT_FAILURE);
}
newargv[0] = argv[1];
execve(argv[1], newargv, newenviron);
perror("execve"); /* execve() only returns on error */
exit(EXIT_FAILURE);
}
script.sh如下：
#!/bin/bash
ls 執行：
./execve ./script.sh
會在當前終端下輸出所有的文件
yca@Ubuntu:~/桌面/hello$ ./execve ./script.sh
1 execve hello1 hello3 hello5 hello_lex
1.txt execve.c hello1.c hello3.cpp hello5.c k_max
Bubble hello hello1.o hello3.o hello5.o k_max.c
Bubble.c hello.c hello2.c hello3.s hello5.s lex.yy.c
QuickSort.c hello.lex hello2.o hello4 hello5.s1 script.sh
Quicksort1.c hello.sh hello2.s hello4.c hello51.s
很好很強大~~
