Display console output 1 or more lines below

Question

When I run a command like tail ~/SOMEFILE I get, for example:

testenv@vps_1:~# tail ~/SOMEFILE
    This is the content of SOMEFILE.

But what if I want to have a carriage return between: testenv@vps_1:~# and the output of: This is the content of SOMEFILE.

So the final result would be like this:

testenv@vps_1:~# tail ~/SOMEFILE

    This is the content of SOMEFILE.

Or this:

testenv@vps_1:~# tail ~/SOMEFILE


    This is the content of SOMEFILE.

Or this:

testenv@vps_1:~# tail ~/SOMEFILE



    This is the content of SOMEFILE.

Note: The first example show one line of spacing between the two parts, the second example show two lines, and the third three lines.

Is there a way to make sure the tail output (or any other output) for that matter would be spaced down as I've shown in the examples, just for this particular command (not for all commands of course), in Bash?

Answer 1

tail doesn't have any argument to manage this.

What you can do as a workaround is printing one empty line before running the tail command.

echo && tail ~/SOMEFILE

For multiple lines: yes command can also be used. yes man page like suggested here: bash: print x number of blank lines

yes '' | sed 5q && tail ~/SOMEFILE

Replace 5 by the amount of empty lines you want.

Note: you may also want to have a look at editing your terminal prompt. But then it will be terminal wide and not only linked to your specific command.

Answer 2

For single empty line

sed '{x;1p;x;}' filename | tail

For 5 empty lines at the beginning

sed '{x;1p;1p;1p;1p;1p;x;}' filename | tail

Answer 3

The simplest option would be printing manually those extra newlines, something like:

printf '\n\n\n'; tail ~/SOMEFILE

But if you want to:

• Do this just for tail
• Not write extra commands with every tail invocation
• Have a simple yet full control over the quantity of newlines

then I recommend you to add a function to your aliases/rc file.

For example:

# Bash version

# In Bash we can override commands with functions
# thanks to the `command` builtin
tail() {

  # `local` limit the scope of variables,
  # so we don't accidentally override global variables (if any).
  local i lines

  # `lines` gets the value of the first positional parameter.
  lines="$1"

  # A C-like iterator to print newlines.
  for ((i=1; i<=lines; i++)); do
    printf '\n'
  done

  # - `command` is a bash builtin, we can use it to run a command.
  #   whose name is the same as our function, so we don't trigger
  #   a fork bomb: <https://en.wikipedia.org/wiki/Fork_bomb>
  #
  # - "${@:2}" is to get the rest of the positional parameters.
  #   If you want, you can rewrite this as:
  #
  #       # `shift` literally shifts the positional parameters
  #       shift
  #       command "${@}"
  #
  #   to avoid using "${@:2}"
  command tail "${@:2}"

}

#===============================================================================

# POSIX version

# POSIX standard does not demand the `command` builtin,
# so we cannot override `tail`.
new_tail() {

  # `lines` gets the value of the first positional parameter.
  lines="$1"

  # `i=1`, `[ "$i" -le "$lines" ]` and `i=$((i + 1))` are the POSIX-compliant
  # equivalents to our C-like iterator in Bash
  i=1
  while [ "$i" -le "$lines" ]; do
    printf '\n'
    i=$((i + 1))
  done

  # Basically the same as Bash version
  shift
  tail "${@}"

}

So you can call it as:

tail 3 ~/SOMEFILE