$ curl cheat.sh/
 cheat.sheets:resize2fs 
# resize2fs

# ext2/ext3/ext4 file system resize tool

# resize filesystem up to the block device size
# make e2fsck /dev/xvdb1 before
# filesystem must be not mounted for ext2
resize2fs /dev/xvdb1

# shrink filesystem (20G is new size)
resize2fs /dev/xvdb1 20G

 tldr:resize2fs 
# resize2fs
# Resize an ext2, ext3 or ext4 filesystem.
# Does not resize the underlying partition. The filesystem may have to be unmounted first, read the man page for more details.
# More information: <https://manned.org/resize2fs>.

# Automatically resize a filesystem:
resize2fs /dev/sdXN

# Resize the filesystem to a size of 40G, displaying a progress bar:
resize2fs -p /dev/sdXN 40G

# Shrink the filesystem to its minimum possible size:
resize2fs -M /dev/sdXN

$
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