Hi Punit,
On my computer this is the output:
echo 'int main(){return 0;}' > main.c
export GTAGSLABEL=pygments
sudo dpkg -i global_6.6.4-3_amd64.deb
gtags -v
[Tue Aug 11 12:58:15 UTC 2020] Gtags started.
Using configuration file '/etc/gtags/gtags.conf'.
Using configuration label 'pygments'.
Using plug-in parser.
[Tue Aug 11 12:58:15 UTC 2020] Creating 'GTAGS' and 'GRTAGS'.
[1] extracting tags of main.c
[Tue Aug 11 12:58:15 UTC 2020] Done.
gtags -d GTAGS
__.COMPNAME __.COMPNAME
__.COMPRESS __.COMPRESS ddefine ttypedef
__.VERSION __.VERSION 6
main 1 @n 1 int @n(){return 0;}
sudo dpkg -i global_6.6.4-4_amd64.deb
gtags -v
[Tue Aug 11 12:59:10 UTC 2020] Gtags started.
Using configuration file '/etc/gtags/gtags.conf'.
Using configuration label 'pygments'.
Using plug-in parser.
[Tue Aug 11 12:59:10 UTC 2020] Creating 'GTAGS' and 'GRTAGS'.
[1] extracting tags of main.c
[Tue Aug 11 12:59:10 UTC 2020] Done.
gtags -d GTAGS
__.COMPNAME __.COMPNAME
__.COMPRESS __.COMPRESS ddefine ttypedef
__.VERSION __.VERSION 6
Gregory
