Case：
~/aaa$ global -xa main
main 3
/home/cstor/aaa/test.cc int main () {
main 1
/home/cstor/aaa/test1.c int main()
main 1
/home/cstor/aaa/test2.sh function main () {
main 1
/home/cstor/aaa/test3.py def main():
~/aaa$
~/aaa$
~/aaa$ global -xaf test.cc
main 3
/home/cstor/aaa/test.cc int main () {
~/aaa$
~/aaa$ global -xaf test3.py
~/aaa$
~/aaa$global -xaf test2.sh
~/aaa$
As can be seen above：
The global -xa main command can find all files containing the main symbol,
which means there is no problem with the gtags command when generating
symbols.
The global -xaf test.cc command can display all the symbols in the test.cc
file.
The outputs of both global -xaf test3.py and global -xaf test2.sh are
empty.
So, I suspect that the -f parameter is only effective for C/C++ language
files.
