Use JQ to manipulate compiledb manually

gistfile1.txt

Show (first):
jq -r '(.[0].arguments | join(" ")) + "    PWD=" + .[0].directory' compile_commands.json

Show (by file, all args):
jq -r '(.[] | select(.file | endswith("dir/file.c"))) | .arguments | join(" ")' compile_commands.json

Show (by file, filtered args):
jq -r '(.[] | select(.file | endswith("dir/file.c"))) | .arguments[] | select(startswith("-m"))' compile_commands.json

Run (first, better):
jq -r '"pushd \"" + .[0].directory + "\" > /dev/null && " + (.[0].arguments | join(" ")) + " ; popd > /dev/null"' compile_commands.json