Question

I want to run the following command from a C program to read the system’s CPU and memory use:

ps aux|awk 'NR > 0 { cpu +=$3; ram+=$4 }; END {print cpu,ram}'

I am trying to pass it to the execl command and after that read its output:

execl("/bin/ps", "/bin/ps", "aux|awk", "'NR > 0 { cpu +=$3; ram+=$4 }; END {print cpu,ram}'",(char *) 0);

But in the terminal I am getting the following error:

ERROR: Unsupported option (BSD syntax)

I would like to know how to properly pass awk as argument to execl?

Answer 1

You can’t do this here this way.

The problem is that you want to execute several commands. execl is for executing a single command. The statement you have is using shell syntax (notably the | )

You will have better luck combining it all up in a single string and using the system(3) call.