ls -la $HOME/playground
total 8
drwxr-s--- 2 root root 4096 May 22 06:26 .
drwxr-s--- 7 root root 4096 May 22 06:26 ..
-rw-r----- 1 root root    0 May 22 06:26 f$i$l$e$3$
-rw-r----- 1 root root    0 May 22 06:26 fi$le1
-rw-r----- 1 root root    0 May 22 06:26 fi\$le4
-rw-r----- 1 root root    0 May 22 06:26 file2$