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UMOUNT(8) Linux Programmer’s Manual UMOUNT(8)
NAME
umount - unmount file systems
-l Lazy unmount. Detach the filesystem from the filesystem hierar-
chy now, and cleanup all references to the filesystem as soon as
it is not busy anymore. This option allows a ‘busy’ filesystem
to be unmounted. (Requires kernel 2.4.11 or later.)
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every command line tool should have a “lazy” option