Debian package:user and group - cmake

Question

Recently,I use cmake/cpack to make a debian package.I make succeed.But I install it on the computer(sudo dpkg -i mypcakge.deb), I find a problem: the install program's user and group is root:root.Due to some reason, my problem should run in a specific user/group. I don't know how to do this, could you help me?
Also, I don't want to modify the user and group with chown(..) after I installed the package.Is there a way to add something in the CMakeLists to do this?

Answer 1

It is not related only to CMake, but in general when using debhelper and/or non-standard usernames.
dh(1) often used in debian/rules by default will call dh_fixperms(1), which will reset owners and permissions by default.
There are basically three ways to retain owners/permissions you want:
if you use some standard Debian system user/group, you may skip
or override dh_fixperms(1) and you may specify files to override owner/group for. Be sure that your package pre-depends on correct version of base-passwd package which contains wanted users/groups.
You could override in your debian/rules like here (see dh_fixperms(1) man page):
override_dh_fixperms:
dh_fixperms --exclude matchname
Debian docs have more info.
if you create your own users and you want files/dirs to be owned by them, you will need to use postinst script. In it, you first need to create users/groups if they don't already exist, and then do something like
chown myuser:mygroup /var/log/mydir
chmod 0750 /var/log/mydir
Alternatively, you can use (also in your postinst and postrm scripts) dpkg-statoverride(8) to change owners,groups and permissions of your (or other) files like this:
for i in /usr/bin/foo /usr/sbin/bar; do
# only do something when no setting exists
if ! dpkg-statoverride --list $i >/dev/null 2>&1; then
#include: debconf processing, question about foo and bar
if [ "$RET" = "true" ] ; then
dpkg-statoverride --update --add sysuser root 4755 $i
fi
fi
done
You should also handle removal, like this:
for i in /usr/bin/foo /usr/sbin/bar; do
if dpkg-statoverride --list $i >/dev/null 2>&1; then
dpkg-statoverride --remove $i
fi
done