Adding a custom operating systems to the berryboot menu

oliver@s /opt/ncp $ **sudo kpartx -av NextCloudPi_10-02-17.img **
add map loop0p1 (252:0): 0 85622 linear 7:0 8192
add map loop0p2 (252:1): 0 5625192 linear 7:0 94208
oliver@s /opt/ncp $ sudo mount /dev/mapper/loop0p2 /mnt
oliver@s /opt/ncp $ sudo sed -i 's/^\/dev\/mmcblk/#\0/g' /mnt/etc/fstab
oliver@s /opt/ncp $ sudo mksquashfs /mnt NextCloudPi_10_02_17_for_berryboot.img -comp lzo -e lib/modules
Parallel mksquashfs: Using 4 processors
Creating 4.0 filesystem on NextCloudPi_10_02_17_for_berryboot.img, block size 131072.
[===================================================================================================================================================================\] 58954/58954 100%

Exportable Squashfs 4.0 filesystem, lzo compressed, data block size 131072
	compressed data, compressed metadata, compressed fragments, compressed xattrs
	duplicates are removed
Filesystem size 545841.02 Kbytes (533.05 Mbytes)
	36.19% of uncompressed filesystem size (1508137.40 Kbytes)
Inode table size 814666 bytes (795.57 Kbytes)
	37.85% of uncompressed inode table size (2152359 bytes)
Directory table size 698003 bytes (681.64 Kbytes)
	49.43% of uncompressed directory table size (1412008 bytes)
Number of duplicate files found 3490
Number of inodes 64046
Number of files 51127
Number of fragments 3527
Number of symbolic links  6475
Number of device nodes 82
Number of fifo nodes 0
Number of socket nodes 32
Number of directories 6330
Number of ids (unique uids + gids) 29
Number of uids 9
	root (0)
	man (6)
	oliver (1000)
	www-data (33)
	systemd-timesync (100)
	avahi-autoipd (109)
	syslog (104)
	messagebus (106)
	colord (111)
Number of gids 26
	root (0)
	video (44)
	audio (29)
	tty (5)
	kmem (15)
	disk (6)
	syslog (108)
	shadow (42)
	ntp (114)
	oliver (1000)
	www-data (33)
	users (100)
	utmp (43)
	crontab (107)
	messagebus (110)
	netdev (109)
	staff (50)
	avahi-autoipd (117)
	man (12)
	lpadmin (113)
	nogroup (65534)
	ssh (116)
	mlocate (115)
	systemd-network (103)
	adm (4)
	mail (8)
oliver@s /opt/ncp $ sudo umount /mnt
oliver@s /opt/ncp $ ls
NextCloudPi_10_02_17_for_berryboot.img	NextCloudPi_10-02-17.img
oliver@s /opt/ncp $ sudo kpartx -d NextCloudPi_10-02-17.img
loop deleted : /dev/loop0
oliver@s /opt/ncp $ ls
NextCloudPi_10_02_17_for_berryboot.img	NextCloudPi_10-02-17.img