CODEWITHSUNDEEP
clinuxcommand-line
Blub
Blub

Reputation: 3822

Piping to system()?

I have a binary that reads input with gets().

I would like to execute it using system() in my own program and pipe input to it. How would this be possible?

On command line I would just do echo 'blabla' | ./a.out. Now I want to basically do the same inside a C program, where the blabla is generated in that program, then a.out is executed and blabla piped to it.

I can not change the first program to accept command line arguments.

Upvotes: 1

Views: 311

Answers (2)

ooga
ooga

Reputation: 15501

Remember that system actually runs a shell, so you can execute any shell command you want, including a pipeline. Unless you're generating output that you need to send in a loop or something like that, popen provides no advantage (in particular, it does not allow you to write to the program's stdin and also read from it's stdout). So you can just use system like this:

// generate the string you want to send
char str[256] = "blabla";

// sprintf it into a command string
char cmd[256];
sprintf(cmd, "echo '%s' | ./a.out", str);

// send the command string to system
system(cmd);

Upvotes: 2

user3553031
user3553031

Reputation: 6214

I have a binary that reads input with gets().

Don't use it. gets() is unsafe to use under any circumstances.

In response to your question, you can use popen() to pipe input into a subprocess.

Upvotes: 4

Related Questions