Input and output redirection in shell

I am trying to implement input and output redirection is C. I read all of the answers to this question, but it does not work! It goes to the last if (execvp).

I want something like this:

output redirection: ls -al > output.txt

input redirection: sort < input.txt

Here is the code that I wrote:

int io_redirection(char * args, char* inputFile, char* outputFile, int option){



    int err = -1;



    int fileDescriptor = -1; // between 0 and 19

    pid_t pid = -10;

    pid = fork();



    if(pid==-1){

        printf("Child process could not be createdn");

        return;

    }

    if(pid==0){

        // Option 0: output redirection

        if (option == 0){

            // I also tried fileDescriptor = creat(outputFile, 0644);

            fileDescriptor = open(outputFile, O_CREAT | O_TRUNC | O_WRONLY, 0600); 

            dup2(fileDescriptor, STDOUT_FILENO); 

            close(fileDescriptor);





        }

         else if (option == 1){

            // Option 1: input redirection



            fileDescriptor = open(inputFile, O_RDONLY, 0600);  

            dup2(fileDescriptor, STDIN_FILENO);

            close(fileDescriptor);



        }







        if (execvp(args[0],args)==err){

            printf("err");

            kill(getpid(),SIGTERM);

        }        

    }

    waitpid(pid,NULL,0);

}

for the output redirection args contains ls and -al. And for the input one it contains sort.

edited Nov 20 '18 at 6:28

asked Nov 20 '18 at 5:18

Setareh

172239

You don't need to test the return value from execvp() — if it returns, it failed; if it succeeds, it doesn't return. You don't seem to have allowed for sort < input.txt > output.txt — both input and output redirection on a single command.

– Jonathan Leffler
Nov 20 '18 at 6:07

Without A Minimal, Complete, and Verifiable Example (MCVE) it is hard to say what state args is in? Have the elements holding '<' or '>' and the filenames already been removed so that only additional arguments remain?

– David C. Rankin
Nov 20 '18 at 6:07

@JonathanLeffler it is not about that, I used this approach multiple times in my code(for example in pipe, and it didn't cause any problem), besides I tried to remove the testing of its return, but in that way, it does not go out of the loop.

– Setareh
Nov 20 '18 at 6:23

@DavidC.Rankin For this example ls -al > output.txt: args contain ls and -al

– Setareh
Nov 20 '18 at 6:23

add a comment |

I am trying to implement input and output redirection is C. I read all of the answers to this question, but it does not work! It goes to the last if (execvp).

I want something like this:

output redirection: ls -al > output.txt

input redirection: sort < input.txt

Here is the code that I wrote:

int io_redirection(char * args, char* inputFile, char* outputFile, int option){



    int err = -1;



    int fileDescriptor = -1; // between 0 and 19

    pid_t pid = -10;

    pid = fork();



    if(pid==-1){

        printf("Child process could not be createdn");

        return;

    }

    if(pid==0){

        // Option 0: output redirection

        if (option == 0){

            // I also tried fileDescriptor = creat(outputFile, 0644);

            fileDescriptor = open(outputFile, O_CREAT | O_TRUNC | O_WRONLY, 0600); 

            dup2(fileDescriptor, STDOUT_FILENO); 

            close(fileDescriptor);





        }

         else if (option == 1){

            // Option 1: input redirection



            fileDescriptor = open(inputFile, O_RDONLY, 0600);  

            dup2(fileDescriptor, STDIN_FILENO);

            close(fileDescriptor);



        }







        if (execvp(args[0],args)==err){

            printf("err");

            kill(getpid(),SIGTERM);

        }        

    }

    waitpid(pid,NULL,0);

}

for the output redirection args contains ls and -al. And for the input one it contains sort.

edited Nov 20 '18 at 6:28

asked Nov 20 '18 at 5:18

Setareh

172239

You don't need to test the return value from execvp() — if it returns, it failed; if it succeeds, it doesn't return. You don't seem to have allowed for sort < input.txt > output.txt — both input and output redirection on a single command.

– Jonathan Leffler
Nov 20 '18 at 6:07

Without A Minimal, Complete, and Verifiable Example (MCVE) it is hard to say what state args is in? Have the elements holding '<' or '>' and the filenames already been removed so that only additional arguments remain?

– David C. Rankin
Nov 20 '18 at 6:07

@JonathanLeffler it is not about that, I used this approach multiple times in my code(for example in pipe, and it didn't cause any problem), besides I tried to remove the testing of its return, but in that way, it does not go out of the loop.

– Setareh
Nov 20 '18 at 6:23

@DavidC.Rankin For this example ls -al > output.txt: args contain ls and -al

– Setareh
Nov 20 '18 at 6:23

add a comment |

I am trying to implement input and output redirection is C. I read all of the answers to this question, but it does not work! It goes to the last if (execvp).

I want something like this:

output redirection: ls -al > output.txt

input redirection: sort < input.txt

Here is the code that I wrote:

int io_redirection(char * args, char* inputFile, char* outputFile, int option){



    int err = -1;



    int fileDescriptor = -1; // between 0 and 19

    pid_t pid = -10;

    pid = fork();



    if(pid==-1){

        printf("Child process could not be createdn");

        return;

    }

    if(pid==0){

        // Option 0: output redirection

        if (option == 0){

            // I also tried fileDescriptor = creat(outputFile, 0644);

            fileDescriptor = open(outputFile, O_CREAT | O_TRUNC | O_WRONLY, 0600); 

            dup2(fileDescriptor, STDOUT_FILENO); 

            close(fileDescriptor);





        }

         else if (option == 1){

            // Option 1: input redirection



            fileDescriptor = open(inputFile, O_RDONLY, 0600);  

            dup2(fileDescriptor, STDIN_FILENO);

            close(fileDescriptor);



        }







        if (execvp(args[0],args)==err){

            printf("err");

            kill(getpid(),SIGTERM);

        }        

    }

    waitpid(pid,NULL,0);

}

for the output redirection args contains ls and -al. And for the input one it contains sort.

edited Nov 20 '18 at 6:28

asked Nov 20 '18 at 5:18

Setareh

172239

I am trying to implement input and output redirection is C. I read all of the answers to this question, but it does not work! It goes to the last if (execvp).

I want something like this:

output redirection: ls -al > output.txt

input redirection: sort < input.txt

Here is the code that I wrote:

int io_redirection(char * args, char* inputFile, char* outputFile, int option){



    int err = -1;



    int fileDescriptor = -1; // between 0 and 19

    pid_t pid = -10;

    pid = fork();



    if(pid==-1){

        printf("Child process could not be createdn");

        return;

    }

    if(pid==0){

        // Option 0: output redirection

        if (option == 0){

            // I also tried fileDescriptor = creat(outputFile, 0644);

            fileDescriptor = open(outputFile, O_CREAT | O_TRUNC | O_WRONLY, 0600); 

            dup2(fileDescriptor, STDOUT_FILENO); 

            close(fileDescriptor);





        }

         else if (option == 1){

            // Option 1: input redirection



            fileDescriptor = open(inputFile, O_RDONLY, 0600);  

            dup2(fileDescriptor, STDIN_FILENO);

            close(fileDescriptor);



        }







        if (execvp(args[0],args)==err){

            printf("err");

            kill(getpid(),SIGTERM);

        }        

    }

    waitpid(pid,NULL,0);

}

for the output redirection args contains ls and -al. And for the input one it contains sort.

c shell io-redirection

edited Nov 20 '18 at 6:28

asked Nov 20 '18 at 5:18

Setareh

172239

edited Nov 20 '18 at 6:28

asked Nov 20 '18 at 5:18

Setareh

172239

edited Nov 20 '18 at 6:28

asked Nov 20 '18 at 5:18

Setareh

172239

asked Nov 20 '18 at 5:18

Setareh

172239

asked Nov 20 '18 at 5:18

Setareh

172239

You don't need to test the return value from execvp() — if it returns, it failed; if it succeeds, it doesn't return. You don't seem to have allowed for sort < input.txt > output.txt — both input and output redirection on a single command.

– Jonathan Leffler
Nov 20 '18 at 6:07

Without A Minimal, Complete, and Verifiable Example (MCVE) it is hard to say what state args is in? Have the elements holding '<' or '>' and the filenames already been removed so that only additional arguments remain?

– David C. Rankin
Nov 20 '18 at 6:07

@JonathanLeffler it is not about that, I used this approach multiple times in my code(for example in pipe, and it didn't cause any problem), besides I tried to remove the testing of its return, but in that way, it does not go out of the loop.

– Setareh
Nov 20 '18 at 6:23

@DavidC.Rankin For this example ls -al > output.txt: args contain ls and -al

– Setareh
Nov 20 '18 at 6:23

add a comment |

You don't need to test the return value from execvp() — if it returns, it failed; if it succeeds, it doesn't return. You don't seem to have allowed for sort < input.txt > output.txt — both input and output redirection on a single command.

– Jonathan Leffler
Nov 20 '18 at 6:07

Without A Minimal, Complete, and Verifiable Example (MCVE) it is hard to say what state args is in? Have the elements holding '<' or '>' and the filenames already been removed so that only additional arguments remain?

– David C. Rankin
Nov 20 '18 at 6:07

@JonathanLeffler it is not about that, I used this approach multiple times in my code(for example in pipe, and it didn't cause any problem), besides I tried to remove the testing of its return, but in that way, it does not go out of the loop.

– Setareh
Nov 20 '18 at 6:23

@DavidC.Rankin For this example ls -al > output.txt: args contain ls and -al

– Setareh
Nov 20 '18 at 6:23

You don't need to test the return value from execvp() — if it returns, it failed; if it succeeds, it doesn't return. You don't seem to have allowed for sort < input.txt > output.txt — both input and output redirection on a single command.

– Jonathan Leffler
Nov 20 '18 at 6:07

Without A Minimal, Complete, and Verifiable Example (MCVE) it is hard to say what state args is in? Have the elements holding '<' or '>' and the filenames already been removed so that only additional arguments remain?

– David C. Rankin
Nov 20 '18 at 6:07

@JonathanLeffler it is not about that, I used this approach multiple times in my code(for example in pipe, and it didn't cause any problem), besides I tried to remove the testing of its return, but in that way, it does not go out of the loop.

– Setareh
Nov 20 '18 at 6:23

@DavidC.Rankin For this example ls -al > output.txt: args contain ls and -al

– Setareh
Nov 20 '18 at 6:23

add a comment |

2 Answers
2

active

oldest

votes

execvp requires a NULL as the last paramter. I am guessing your command synthesis ignores that, the rest works as intended.

#include<stdio.h>

#include<stdlib.h>

#include<unistd.h>

#include<string.h>

#include<fcntl.h>

#include<signal.h>

#include<sys/wait.h>





void print_child_status (int status) {

  if (WIFEXITED (status)) {

    fprintf (stdout, "Child exited with status %dn", WEXITSTATUS (status));

  } else if (WIFSTOPPED (status)) {

    fprintf (stdout, "Child stopped by signal %d (%s)n", WSTOPSIG (status), strsignal (WSTOPSIG (status)));

  } else if (WIFSIGNALED (status)) {

    fprintf (stdout, "Child killed by signal %d (%s)n", WTERMSIG (status), strsignal (WTERMSIG (status)));

  } else {

    fprintf (stdout, "Unknown child statusn");

  }

}



int io_redirection(char * args, char* inputFile, char* outputFile, int option){



    int err = -1;



    int fileDescriptor = -1; // between 0 and 19

    pid_t pid = -10;

    pid = fork();



    if(pid==-1){

        printf("Child process could not be createdn");

        return -1;

    }

    else if(pid == 0){

        // Option 0: output redirection

        if (option == 0){

            // I also tried fileDescriptor = creat(outputFile, 0644);

            fileDescriptor = open(outputFile, O_CREAT | O_TRUNC | O_WRONLY, 0600); 

            dup2(fileDescriptor, STDOUT_FILENO); 

            close(fileDescriptor);





        }

         else if (option == 1) {

            // Option 1: input redirection

            fileDescriptor = open(inputFile, O_RDONLY);

             printf("Input redirection %dn", fileDescriptor);

            dup2(fileDescriptor, STDIN_FILENO);

            close(fileDescriptor);



        }

        err = execvp(args[0], args);



        if (err){

            printf("err %dn", err);

        }

        return err;

    } else {

        int status;

        waitpid(pid, &status,0);

        print_child_status(status);

    }

    return 0;



}



int main() {

    char * args = {"ls", "-l", NULL};

    io_redirection(args, NULL, "out.txt", 0);

    char * args1 = {"grep", "main", NULL};

    io_redirection(args1, "./test.c", NULL, 1);

    return 0;

}

answered Nov 20 '18 at 6:26

Luv

1556

It worked. Thank you ooh, what a big mistake.

– Setareh
Nov 20 '18 at 6:40

But still it does not work for the input redirection

– Setareh
Nov 20 '18 at 6:42

1

It works for me, check the status of open(), you could be referring a file that does not exist.

– Luv
Nov 20 '18 at 6:43

add a comment |

Maybe your test wrong, I use the following code test is right.

int main() {

  char* argv = {"ls", "-al", NULL};

  io_redirection(argv, NULL, "test", 0);



  return 0;

}

answered Nov 20 '18 at 6:32

Yunbin Liu

1,162313

Yeah, it was my mistake, I fixed that. It works for output redirection, but it does not for the input one

– Setareh
Nov 20 '18 at 6:43

Make sure the input file exists and has sufficient permissions to open it , and how do you test it? @Setareh

– Yunbin Liu
Nov 20 '18 at 6:48

add a comment |

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2 Answers
2

active

oldest

votes

2 Answers
2

active

oldest

votes

execvp requires a NULL as the last paramter. I am guessing your command synthesis ignores that, the rest works as intended.

#include<stdio.h>

#include<stdlib.h>

#include<unistd.h>

#include<string.h>

#include<fcntl.h>

#include<signal.h>

#include<sys/wait.h>





void print_child_status (int status) {

  if (WIFEXITED (status)) {

    fprintf (stdout, "Child exited with status %dn", WEXITSTATUS (status));

  } else if (WIFSTOPPED (status)) {

    fprintf (stdout, "Child stopped by signal %d (%s)n", WSTOPSIG (status), strsignal (WSTOPSIG (status)));

  } else if (WIFSIGNALED (status)) {

    fprintf (stdout, "Child killed by signal %d (%s)n", WTERMSIG (status), strsignal (WTERMSIG (status)));

  } else {

    fprintf (stdout, "Unknown child statusn");

  }

}



int io_redirection(char * args, char* inputFile, char* outputFile, int option){



    int err = -1;



    int fileDescriptor = -1; // between 0 and 19

    pid_t pid = -10;

    pid = fork();



    if(pid==-1){

        printf("Child process could not be createdn");

        return -1;

    }

    else if(pid == 0){

        // Option 0: output redirection

        if (option == 0){

            // I also tried fileDescriptor = creat(outputFile, 0644);

            fileDescriptor = open(outputFile, O_CREAT | O_TRUNC | O_WRONLY, 0600); 

            dup2(fileDescriptor, STDOUT_FILENO); 

            close(fileDescriptor);





        }

         else if (option == 1) {

            // Option 1: input redirection

            fileDescriptor = open(inputFile, O_RDONLY);

             printf("Input redirection %dn", fileDescriptor);

            dup2(fileDescriptor, STDIN_FILENO);

            close(fileDescriptor);



        }

        err = execvp(args[0], args);



        if (err){

            printf("err %dn", err);

        }

        return err;

    } else {

        int status;

        waitpid(pid, &status,0);

        print_child_status(status);

    }

    return 0;



}



int main() {

    char * args = {"ls", "-l", NULL};

    io_redirection(args, NULL, "out.txt", 0);

    char * args1 = {"grep", "main", NULL};

    io_redirection(args1, "./test.c", NULL, 1);

    return 0;

}

answered Nov 20 '18 at 6:26

Luv

1556

It worked. Thank you ooh, what a big mistake.

– Setareh
Nov 20 '18 at 6:40

But still it does not work for the input redirection

– Setareh
Nov 20 '18 at 6:42

1

It works for me, check the status of open(), you could be referring a file that does not exist.

– Luv
Nov 20 '18 at 6:43

add a comment |

execvp requires a NULL as the last paramter. I am guessing your command synthesis ignores that, the rest works as intended.

#include<stdio.h>

#include<stdlib.h>

#include<unistd.h>

#include<string.h>

#include<fcntl.h>

#include<signal.h>

#include<sys/wait.h>





void print_child_status (int status) {

  if (WIFEXITED (status)) {

    fprintf (stdout, "Child exited with status %dn", WEXITSTATUS (status));

  } else if (WIFSTOPPED (status)) {

    fprintf (stdout, "Child stopped by signal %d (%s)n", WSTOPSIG (status), strsignal (WSTOPSIG (status)));

  } else if (WIFSIGNALED (status)) {

    fprintf (stdout, "Child killed by signal %d (%s)n", WTERMSIG (status), strsignal (WTERMSIG (status)));

  } else {

    fprintf (stdout, "Unknown child statusn");

  }

}



int io_redirection(char * args, char* inputFile, char* outputFile, int option){



    int err = -1;



    int fileDescriptor = -1; // between 0 and 19

    pid_t pid = -10;

    pid = fork();



    if(pid==-1){

        printf("Child process could not be createdn");

        return -1;

    }

    else if(pid == 0){

        // Option 0: output redirection

        if (option == 0){

            // I also tried fileDescriptor = creat(outputFile, 0644);

            fileDescriptor = open(outputFile, O_CREAT | O_TRUNC | O_WRONLY, 0600); 

            dup2(fileDescriptor, STDOUT_FILENO); 

            close(fileDescriptor);





        }

         else if (option == 1) {

            // Option 1: input redirection

            fileDescriptor = open(inputFile, O_RDONLY);

             printf("Input redirection %dn", fileDescriptor);

            dup2(fileDescriptor, STDIN_FILENO);

            close(fileDescriptor);



        }

        err = execvp(args[0], args);



        if (err){

            printf("err %dn", err);

        }

        return err;

    } else {

        int status;

        waitpid(pid, &status,0);

        print_child_status(status);

    }

    return 0;



}



int main() {

    char * args = {"ls", "-l", NULL};

    io_redirection(args, NULL, "out.txt", 0);

    char * args1 = {"grep", "main", NULL};

    io_redirection(args1, "./test.c", NULL, 1);

    return 0;

}

answered Nov 20 '18 at 6:26

Luv

1556

It worked. Thank you ooh, what a big mistake.

– Setareh
Nov 20 '18 at 6:40

But still it does not work for the input redirection

– Setareh
Nov 20 '18 at 6:42

1

It works for me, check the status of open(), you could be referring a file that does not exist.

– Luv
Nov 20 '18 at 6:43

add a comment |

execvp requires a NULL as the last paramter. I am guessing your command synthesis ignores that, the rest works as intended.

#include<stdio.h>

#include<stdlib.h>

#include<unistd.h>

#include<string.h>

#include<fcntl.h>

#include<signal.h>

#include<sys/wait.h>





void print_child_status (int status) {

  if (WIFEXITED (status)) {

    fprintf (stdout, "Child exited with status %dn", WEXITSTATUS (status));

  } else if (WIFSTOPPED (status)) {

    fprintf (stdout, "Child stopped by signal %d (%s)n", WSTOPSIG (status), strsignal (WSTOPSIG (status)));

  } else if (WIFSIGNALED (status)) {

    fprintf (stdout, "Child killed by signal %d (%s)n", WTERMSIG (status), strsignal (WTERMSIG (status)));

  } else {

    fprintf (stdout, "Unknown child statusn");

  }

}



int io_redirection(char * args, char* inputFile, char* outputFile, int option){



    int err = -1;



    int fileDescriptor = -1; // between 0 and 19

    pid_t pid = -10;

    pid = fork();



    if(pid==-1){

        printf("Child process could not be createdn");

        return -1;

    }

    else if(pid == 0){

        // Option 0: output redirection

        if (option == 0){

            // I also tried fileDescriptor = creat(outputFile, 0644);

            fileDescriptor = open(outputFile, O_CREAT | O_TRUNC | O_WRONLY, 0600); 

            dup2(fileDescriptor, STDOUT_FILENO); 

            close(fileDescriptor);





        }

         else if (option == 1) {

            // Option 1: input redirection

            fileDescriptor = open(inputFile, O_RDONLY);

             printf("Input redirection %dn", fileDescriptor);

            dup2(fileDescriptor, STDIN_FILENO);

            close(fileDescriptor);



        }

        err = execvp(args[0], args);



        if (err){

            printf("err %dn", err);

        }

        return err;

    } else {

        int status;

        waitpid(pid, &status,0);

        print_child_status(status);

    }

    return 0;



}



int main() {

    char * args = {"ls", "-l", NULL};

    io_redirection(args, NULL, "out.txt", 0);

    char * args1 = {"grep", "main", NULL};

    io_redirection(args1, "./test.c", NULL, 1);

    return 0;

}

answered Nov 20 '18 at 6:26

Luv

1556

execvp requires a NULL as the last paramter. I am guessing your command synthesis ignores that, the rest works as intended.

#include<stdio.h>

#include<stdlib.h>

#include<unistd.h>

#include<string.h>

#include<fcntl.h>

#include<signal.h>

#include<sys/wait.h>





void print_child_status (int status) {

  if (WIFEXITED (status)) {

    fprintf (stdout, "Child exited with status %dn", WEXITSTATUS (status));

  } else if (WIFSTOPPED (status)) {

    fprintf (stdout, "Child stopped by signal %d (%s)n", WSTOPSIG (status), strsignal (WSTOPSIG (status)));

  } else if (WIFSIGNALED (status)) {

    fprintf (stdout, "Child killed by signal %d (%s)n", WTERMSIG (status), strsignal (WTERMSIG (status)));

  } else {

    fprintf (stdout, "Unknown child statusn");

  }

}



int io_redirection(char * args, char* inputFile, char* outputFile, int option){



    int err = -1;



    int fileDescriptor = -1; // between 0 and 19

    pid_t pid = -10;

    pid = fork();



    if(pid==-1){

        printf("Child process could not be createdn");

        return -1;

    }

    else if(pid == 0){

        // Option 0: output redirection

        if (option == 0){

            // I also tried fileDescriptor = creat(outputFile, 0644);

            fileDescriptor = open(outputFile, O_CREAT | O_TRUNC | O_WRONLY, 0600); 

            dup2(fileDescriptor, STDOUT_FILENO); 

            close(fileDescriptor);





        }

         else if (option == 1) {

            // Option 1: input redirection

            fileDescriptor = open(inputFile, O_RDONLY);

             printf("Input redirection %dn", fileDescriptor);

            dup2(fileDescriptor, STDIN_FILENO);

            close(fileDescriptor);



        }

        err = execvp(args[0], args);



        if (err){

            printf("err %dn", err);

        }

        return err;

    } else {

        int status;

        waitpid(pid, &status,0);

        print_child_status(status);

    }

    return 0;



}



int main() {

    char * args = {"ls", "-l", NULL};

    io_redirection(args, NULL, "out.txt", 0);

    char * args1 = {"grep", "main", NULL};

    io_redirection(args1, "./test.c", NULL, 1);

    return 0;

}

answered Nov 20 '18 at 6:26

Luv

1556

answered Nov 20 '18 at 6:26

Luv

1556

answered Nov 20 '18 at 6:26

Luv

1556

answered Nov 20 '18 at 6:26

Luv

1556

It worked. Thank you ooh, what a big mistake.

– Setareh
Nov 20 '18 at 6:40

But still it does not work for the input redirection

– Setareh
Nov 20 '18 at 6:42

1

It works for me, check the status of open(), you could be referring a file that does not exist.

– Luv
Nov 20 '18 at 6:43

add a comment |

It worked. Thank you ooh, what a big mistake.

– Setareh
Nov 20 '18 at 6:40

But still it does not work for the input redirection

– Setareh
Nov 20 '18 at 6:42

1

It works for me, check the status of open(), you could be referring a file that does not exist.

– Luv
Nov 20 '18 at 6:43

It worked. Thank you ooh, what a big mistake.

– Setareh
Nov 20 '18 at 6:40

But still it does not work for the input redirection

– Setareh
Nov 20 '18 at 6:42

It works for me, check the status of open(), you could be referring a file that does not exist.

– Luv
Nov 20 '18 at 6:43

add a comment |

Maybe your test wrong, I use the following code test is right.

int main() {

  char* argv = {"ls", "-al", NULL};

  io_redirection(argv, NULL, "test", 0);



  return 0;

}

answered Nov 20 '18 at 6:32

Yunbin Liu

1,162313

Yeah, it was my mistake, I fixed that. It works for output redirection, but it does not for the input one

– Setareh
Nov 20 '18 at 6:43

Make sure the input file exists and has sufficient permissions to open it , and how do you test it? @Setareh

– Yunbin Liu
Nov 20 '18 at 6:48

add a comment |

Maybe your test wrong, I use the following code test is right.

int main() {

  char* argv = {"ls", "-al", NULL};

  io_redirection(argv, NULL, "test", 0);



  return 0;

}

answered Nov 20 '18 at 6:32

Yunbin Liu

1,162313

Yeah, it was my mistake, I fixed that. It works for output redirection, but it does not for the input one

– Setareh
Nov 20 '18 at 6:43

Make sure the input file exists and has sufficient permissions to open it , and how do you test it? @Setareh

– Yunbin Liu
Nov 20 '18 at 6:48

add a comment |

Maybe your test wrong, I use the following code test is right.

int main() {

  char* argv = {"ls", "-al", NULL};

  io_redirection(argv, NULL, "test", 0);



  return 0;

}

answered Nov 20 '18 at 6:32

Yunbin Liu

1,162313

Maybe your test wrong, I use the following code test is right.

int main() {

  char* argv = {"ls", "-al", NULL};

  io_redirection(argv, NULL, "test", 0);



  return 0;

}

answered Nov 20 '18 at 6:32

Yunbin Liu

1,162313

answered Nov 20 '18 at 6:32

Yunbin Liu

1,162313

answered Nov 20 '18 at 6:32

Yunbin Liu

1,162313

answered Nov 20 '18 at 6:32

Yunbin Liu

1,162313

Yeah, it was my mistake, I fixed that. It works for output redirection, but it does not for the input one

– Setareh
Nov 20 '18 at 6:43

Make sure the input file exists and has sufficient permissions to open it , and how do you test it? @Setareh

– Yunbin Liu
Nov 20 '18 at 6:48

add a comment |

Yeah, it was my mistake, I fixed that. It works for output redirection, but it does not for the input one

– Setareh
Nov 20 '18 at 6:43

Make sure the input file exists and has sufficient permissions to open it , and how do you test it? @Setareh

– Yunbin Liu
Nov 20 '18 at 6:48

Yeah, it was my mistake, I fixed that. It works for output redirection, but it does not for the input one

– Setareh
Nov 20 '18 at 6:43

Make sure the input file exists and has sufficient permissions to open it , and how do you test it? @Setareh

– Yunbin Liu
Nov 20 '18 at 6:48

add a comment |

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