CODEWITHSUNDEEP
clinuxshell
Jiayi Guo
Jiayi Guo

Reputation: 103

Send Linux command from C program

I'm writing a C program to run in Linux shell. Now I got a problem with such command.

#include <stdio.h>
void main()
{
char* command="history>>history";
system(command);
}

I want it to write the result of command "history" into a document, but it failed with a blank one.

If I change it to "date>>history", current system time will be written into the document.

Is there any problem with "history>>history"? What should I do if I want to get that work? Thanks!

Upvotes: 1

Views: 1296

Answers (1)

Pik&#39;
Pik&#39;

Reputation: 7067

The problem is that history is not a real command but a shell builtin. Thus you can't call it from a C program[1].

Depending on the shell the user is using, you can instead get the history from ~/.bash_history, ~/.zsh_history and so on. Note however that zsh only write to this file at the end of a session.

[1] Well, you could theorically try system("bash -c history"), but you won't get the actual history because the builtin isn't run in the context of the current session.

Upvotes: 5

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