/ld: /usr/lib/debug/usr/lib/x86_64-linux-gnu/crt1.o(.debug_info): relocation 0 has invalid symbol indexsymbol index 12
/usr/bin/ld: /usr/lib/debug/usr/lib/x86_64-linux-gnu/cr
/x86_64-linux-gnu -isystem /usr/include /home/zxy/understanding-unix-linux-programming/ch7/sigactdemo.c/ch7/sigactdemo.c, index may be incomplete
E[17:12:54.593] Failed to write background-index s