Create a directory: mkdir, plus recursively create -P
touch: create a file or modify file time information
-a modify access access time
-m modify modify modify time
-d modify access and modify time
rm: Delete command
-f Forces deletion
-r delete a directory
dd: Copy the file conversion according to the size or the number of blocks and
If the input file name
the name of the output file
count the number of sub-blocks
block size bs
file: Check file types