Question

Is it recommended to call shell commands from a C program in C using system() ?

I want to develop a web crawler in C and want to use wget to fetch content from a URL ?
Should I do it using system(” wget …”)?

Answer 1

Regardless of the programming language, calling system shell should really be the last resort when nothing else works, because:

• It almost surely will not work under other operating system.
• The error handling is actually complex (you need to capture and parse the error stream). Frequently this is just not done and all errors are ignored.
• If you port such an application to another platform, all called tools must be ported as well.

The same wget was a problem for us when we were porting some nasty perl code to mobile device. While just from Linux to Linux, we discovered that “standard” wget has some switches BusyBox does not support so needed to port wget as well, and later even grep as if perl would not have its own pattern search. After that I am fully convinced that better no.