How to get permission number by string : -rw-r--r-- What do you mean by “set the same”? Do you already have a file with -rw-r--r-- permission and want to set another file with the same permissions? Then see if your chmod supports --reference: “--reference=RFILE use RFILE's mode instead of MODE values” – man chmod
How to use casper-rw file for persistence - Unix Linux Stack Exchange So you'd need to situate a casper-rw file (it's a single file with a filesystem within too) in a location that's physically on the USB drive Making a writable filesystem The Pendrive Linux website shows some details on how to go about creating a casper-rw filesystem The article is titled: Create a larger casper-rw loop file in Linux
Make all new files in a directory accessible to a group If ACLs are not an option, make the directory owned by the group GROUPNAME, and set its permissions to 2775 or 2770: chmod g+rwxs path to directory The s here means the setgid bit; for a directory, it means that files created in this directory will belong to the group that owns the directory You'll also need to set Alice and Bob's umask to make all their files group-writable by default The
mount - Mounting a squashfs filesystem in read-write - Unix Linux . . . Using overlayfs as shown is the best way to have pseudo "squashfs rw" ; It requires however to run on > 4 x kernel (or ubuntu >14 x trusty ) An alternative solution when one is sitting on older live cd without any overlayfs aufs unionfs is to make use of squashfs'own capabilities