Refactor to use gdb printf

scripts/backtrace-from-core

@@ -56,30 +56,30 @@ log1 'Generating backtrace...'
 gdb "$fspath" "$core" > $btpath <<'EOF'
 set prompt
 set pagination off
-echo \n\n
-echo ================================================================================\n
-echo # GDB session generated by FS backtrace-from-core\n
-echo ================================================================================\n
-echo \n\n
-echo ================================================================================\n
-echo # info threads\n
-echo ================================================================================\n
+printf "\n\n"
+printf "================================================================================\n"
+printf "# GDB session generated by FS backtrace-from-core\n"
+printf "================================================================================\n"
+printf "\n\n"
+printf "================================================================================\n"
+printf "# info threads\n"
+printf "================================================================================\n"
 info threads
-echo ================================================================================\n
-echo # bt\n
-echo ================================================================================\n
+printf "================================================================================\n"
+printf "# bt\n"
+printf "================================================================================\n"
 bt
-echo ================================================================================\n
-echo # bt full\n
-echo ================================================================================\n
+printf "================================================================================\n"
+printf "# bt full\n"
+printf "================================================================================\n"
 bt full
-echo ================================================================================\n
-echo # thread apply all bt\n
-echo ================================================================================\n
+printf "================================================================================\n"
+printf "# thread apply all bt\n"
+printf "================================================================================\n"
 thread apply all bt
-echo ================================================================================\n
-echo # thread apply all bt full\n
-echo ================================================================================\n
+printf "================================================================================\n"
+printf "# thread apply all bt full\n"
+printf "================================================================================\n"
 thread apply all bt full
 quit
 EOF