ken@ganymede: ~/tmp
$ cat pm_file_insert_re.file
early text
echo ":os:5.7:" >> /mnt/install_list
middle text
echo ":app:name-here:" >> /mnt/install_list
later text
ken@ganymede: ~/tmp
$ pm_file_insert_re.pl
ken@ganymede: ~/tmp
$ cat pm_file_insert_re.file
early text
echo ":os:5.7:" >> /mnt/install_list
middle text
echo ":app:name-here:" >> /mnt/install_list
echo ":app:new-name-here:" >> /mnt/install_list
later text
ken@ganymede: ~/tmp
$