[noname@localhost lib_test]$ ls -l
total 8
-rw-r--r-- 1 noname noname 2816 Jan 14 00:13 libtest.a
-rw-r--r-- 1 noname noname  111 Jan 14 00:02 main.cpp
[noname@localhost lib_test]$ ranlib libtest.a
[noname@localhost lib_test]$ g++ main.cpp -L. -ltest
./libtest.a: could not read symbols: Archive has no index; run ranlib to add one
collect2: ld returned 1 exit status
[noname@localhost lib_test]$