I use use ip by system("ip link set eth0 up") in a C program. I know that system returns -1 if it fails and returns what the called function returns(exit). E.g., if eth0 is not exist on the system, it returns 256. Where can I find what these numerical values defined for ip?
For example ifconfig's Return Codes:
Return Code Description
0 The command completed successfully.
4 The command completed successfully, but a warning condition was detected.
8 The command was not specified correctly.
12 An error was encountered.
16 An unexpected condition was encountered.
