Can I set a linux program to be started and attached by gdb?

Question

On windows, I can set globalflag to associate the start of a program with a debugger, so even when I call a program from a script, the debugger will start my program and is able to break at some code line.

So how to do this with gdb on linux? E.g, I've /home/my/a.out compiled with -g option by gcc, I wish who ever calls into a.out, it will be brought up by gdb:

1. Do I have to modify some system file to say, /home/my/a.out should be started by gdb and automatically attach?

2. How to make gdb auto-attach it and then break at 'main' and run?

Answer 1

Do I have to modify some system file to say, /home/my/a.out should be started by gdb and automatically attach?

You don't need to modify any system files to achive this. Modify /home/my/a.out instead.

Move original binary to a new name:

mv /home/my/a.out /home/my/a.out.orig

Replace /home/my/a.out with a shell script:

cat > /home/my/a.out <<'EOF'
#!/bin/sh
exec gdb -ex start --args /home/my/a.out.orig "$@"
EOF
chmmod +x /home/my/a.out

How to make gdb auto-attach it and then break at 'main' and run?

Above script will do that automatically.