[VIM] Insert the content of a file into current opened file

read a file and insert it into the position below the cursor of the current file

:read /path/to/file

:re /path/to/file

:r /path/to/file

• insert into the beginning of the file

:0r /path/to/file

• insert into the end of the file

:$r /path/to/file

read the output of system command and insert into the position below the cursor of the current file

• read in the file list by ls command

    :r !ls
  
    :r !ls ~

• read in the dir tree by tree command

    :r !tree

read a specific lines from a file and insert it into the position below the cursor of the current file

• read the line no.10 to 20 into current file

:r !sed -n 10,20p /path/to/file