postinst is in php7.2-curl 7.2.3-1ubuntu1.
This file is a maintainer script. It is executed when installing (*inst) or removing (*rm) the package.
The actual contents of the file can be viewed below.
| 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 | #!/bin/sh
set -e
if [ "$1" = "configure" ]; then
    # Install the new versioned configuration
    inidir=/etc/php/7.2/mods-available
    if [ -e /usr/lib/php/php-maintscript-helper ] ; then
	. /usr/lib/php/php-maintscript-helper
	for dsoname in curl; do
	    inifile=${dsoname}.ini
	    # Register new conffile with UCF
	    ucf /usr/share/php7.2-curl/curl/${inifile} ${inidir}/${inifile}
	    ucfr --force php7.2-curl ${inidir}/${inifile}
	    
	    if [ -f "${inidir}/${inifile}.dpkg-new" ]; then
		md5sum="$(md5sum ${inidir}/${inifile}.dpkg-new | sed -e 's/ .*//')"
		old_md5sum="$(md5sum ${inidir}/${inifile} | sed -e 's/ .*//')"
		if [ "$md5sum" = "$old_md5sum" ]; then
		    mv "${inidir}/${inifile}.dpkg-new" "${inidir}/${inifile}"
		fi
	    fi
	
	    php_invoke enmod 7.2 ALL ${dsoname}
	done
    fi
fi
exit 0
 |