rahul@ubuntu:/# df -T
Filesystem     Type     1K-blocks    Used Available Use% Mounted on
udev           devtmpfs   4069692       0   4069692   0% /dev
tmpfs          tmpfs       817552   33924    783628   5% /run
/dev/vda1      ext4      81399452 4942508  76440560   7% /
tmpfs          tmpfs      4087756     136   4087620   1% /dev/shm
tmpfs          tmpfs         5120       0      5120   0% /run/lock
tmpfs          tmpfs      4087756       0   4087756   0% /sys/fs/cgroup
cgmfs          tmpfs          100       0       100   0% /run/cgmanager/fs
tmpfs          tmpfs       817552      48    817504   1% /run/user/1000
tmpfs          tmpfs       817552       0    817552   0% /run/user/1001
rahul@ubuntu:/# echo "hello world" > test.txt
rahul@ubuntu:/# chmod 200 test.txt
rahul@ubuntu:/# ls -lrt /test.txt
--w------- 1 root root 12 Mar  7 17:25 /test.txt
rahul@ubuntu:/# cat /test.txt
hello world
rahul@ubuntu:/#