您好,感谢您的关注。我正在编写自己的shell,并且将输出重定向到文件时遇到小问题。例如,用户写道:ls -l>>输出。如果我找到“>>”,我应该重定向命令的第一部分,我的意思是调用效果ls -l到文件“output”。我尝试在案例1中执行此操作,但是文件被重定向到一个通道并且程序停止,没有出现“Shell - >”并且没有任何进行。你能提出一些建议来解决这个问题吗?感谢。
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <signal.h>
#include <string.h>
#include <sys/wait.h>
#include <sys/types.h>
#include <ctype.h>
#include <errno.h>
#include <sys/stat.h>
#include <fcntl.h>
int *parse(char *linia, char **argv)
{
int counter = -1;
while (*linia != '\0')
{
while (*linia == ' ' || *linia == '\t' || *linia == '\n')
*linia++ = '\0';
*argv++ = linia;
counter++;
while (*linia != '\0' && *linia != ' ' && *linia != '\t' && *linia != '\n')
linia++;
}
*argv = '\0';
return counter;
}
void execute(char **argv)
{
pid_t pid;
int status;
if ((pid = fork()) < 0)
{
printf("*** ERROR ***\n");
exit(1);
}
else if (pid == 0)
{
if (execvp(*argv, argv) < 0)
{
printf("*** ERROR ***\n");
exit(1);
}
}
else
{
while (wait(&status) != pid);
}
}
int specialChar(char *argv)
{
int i=0;
while(argv[i]!='\0')
{
if(argv[i]=='>' && argv[i+1]=='>')
return 1;
else if(argv[i]=='&')
return 2;
else if(argv[i]=='|')
return 3;
i++;
}
}
void main()
{
char command[20];
char *argv[64];
char **history = (char**)malloc(20*sizeof(char*));
int counter1=-1;
int counter2=0;
for(counter2 = 0; counter2<20; counter2++)
{
history[counter2]=(char*)malloc(100*sizeof(char));
}
int start = 0;
FILE *file;
file=fopen("his", "w");
if(!file)
printf("ERROR");
int i=0;
while (1)
{
printf("Shell -> ");
gets(command);
counter1++;
strcpy(history[counter1],command);
fopen("his", "w");
if(counter1<20)
for(i=0; i<=counter1; i++)
{
fprintf(file,"%s\n",history[i]);
}
else
for(i=counter1-20; i<counter1; i++)
{
fprintf(file,"%s\n",history[i]);
}
fflush(file);
printf("\n");
switch(specialChar(command))
{
case 1:
i = parse(command, argv);
int file1 = open(argv[i], O_APPEND | O_WRONLY);
dup2(file1,1) ;
if (strcmp(argv[0], "exit") == 0)
exit(0);
execute(argv);
close(file1);
break;
case 2:
break;
case 3:
break;
default:
parse(command, argv);
if (strcmp(argv[0], "exit") == 0)
exit(0);
execute(argv);
break;
}
fclose(file);
}
}