how can I pass a parameter to the system function with quotes?

Question

I'm trying to reduce columns of top funcion and save it into a file but I don't know how do it using system() function with quotes. I'm doing it like this:

system("top -b n1 | grep \"^ \" | awk '{ printf(\"%s %s %s %s %s %s %s\n\", $1, $2, $8, $3, $9, $10, $12); }' >> file

I'm pretty sure the problem is with the quotes, can someone help me?

what makes you think it is the quotes? What happens when you compile and run the code? — 463035818_is_not_an_ai, Nov 02 '20 at 15:14
If you are using c++11 or greater you can use raw string literals to avoid having to escape. Related: [https://stackoverflow.com/questions/56710024/what-is-a-raw-string](https://stackoverflow.com/questions/56710024/what-is-a-raw-string) — drescherjm, Nov 02 '20 at 15:25

Sander · Accepted Answer · 2020-11-02T15:56:35.007

The problem is not with your quotes. First, you are missing a closing "), and I'm not sure how you are trying to use the variable file but it looks like you are mixing up strings with variables. Make sure that the variable file is indeed used as a variable when you add it to your command string. Lastly, you are escaping \n wrong which messes up your output. You should escape that backslash, so you need to type \\n to wind up with \n in your awk command.

This should work:

string file = "test.txt"; 
system((string("top -b n1 | grep \"^ \" | awk '{ printf(\"%s  %s  %s  %s  %s  %s  %s\\n\", $1, $2, $8, $3, $9, $10, $12); }' >> ") + file).c_str());

how can I pass a parameter to the system function with quotes?

1 Answers1