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/********************************************************************
name: simple shell(shk.c)
written by: 1jjk
E-mail: lingjiujianke@gmail.com
compile: [ljjk @ljjk ljjk]#gcc -O2 -Wall -o shk shk.c
for example: [ljjk @ljjk ljjk]#./shk1
>/bin/ls
shk.c shk
>Ctrl+c
>
********************************************************************/
#include<stdio.h>
#include<stdlib.h>
#include<sys/types.h>
#include<unistd.h>
#include<string.h>
#include<sys/wait.h>
#include<signal.h>
#define MAX 128
void evl(char *cmdlin);
int parse(char *cmdline, char **argv);
int build(char **argv);
char *Fgets(char *ptr,int n, FILE *fp)
{
char *rptr;
if(((rptr=fgets(ptr,n,fp))==NULL)&&ferror(fp))
{
printf("fgets error\r\n");
}
return rptr;
}
int main(int argc,char **argv, char **env)
{
char cmd[MAX];
while(1){
fprintf(stdout,"> ");
if(signal(SIGINT,main)==SIG_ERR)
fprintf(stdout,"signal error\r\n");
Fgets(cmd,MAX,stdin);
if(feof(stdin))
{
exit(0);
}
evl(cmd);
}
}
void evl(char *cmdline)
{
char *argv[MAX];
int bg;
pid_t pid=0;
bg=parse(cmdline,argv);
if(argv[0]==NULL)
return ;
if(!build(argv))
{
if((pid=fork())==0)
if(execve(argv[0],argv,NULL)<0)
{
fprintf(stdout,"%s command not found.\r\n",argv[0]);
exit(0);
}
}
if(!bg)
{
int sta;
if(waitpid(pid, &sta,0)<0)
{
fprintf(stderr,"waitpid error\r\n");
}
else
{
fprintf(stdout,"%d %s",pid,cmdline);
}
}
return;
}
int build(char **argv)
{
if(!strcmp(argv[0], "quit")||!strcmp(argv[0],"exit"))
exit(0);
if(!strcmp(argv[0], "&"))
return 1;
if(!strcmp(argv[0], "ls"))
fprintf(stdout,"sssss\n");
return 0;
}
int parse(char *buf, char **arv)
{
char *delim=NULL;
int arg,bg;
//char *buf=NULL;
buf[strlen(buf)-1]=' ';
while(*buf&&(*buf==' '))
buf++;
arg=0;
while((delim = strchr(buf, ' ')))
{
arv[arg++]=buf;
*delim='\0';
buf=delim+1;
while(*buf&&(*buf==' '))
buf++;
}
arv[arg++]=NULL;
if(arg==0)
return 1;
if((bg=(arv[arg-1]=='&'))!=0)
arv[--arg]=NULL;
return bg;
}
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