Ubuntu – Bash for loop with range {#..#}

The problem is that || and && only skip one subsequent stanza of a command chain when the condition fails. If you write out a full block structure it makes perfect sense. What you wrote becomes this:

if ! true ; then
   echo "This shouldn't print"
else
   exit
fi

What you want is this:

if ! true ; then
   echo "This shouldn't print"
   exit
fi

When you are using Bash's shortcut conditional operators it is better to avoid mixing them. The logic is much easier to understand while you're writing it, and your readers will appreciate your good style.

• http://mywiki.wooledge.org/BashGuide/TestsAndConditionals#Control_Operators
• http://mywiki.wooledge.org/BashPitfalls#cmd1_.26.26_cmd2_.7C.7C_cmd3

In general, short of modifying the command's code (and recompiling, in the case of a compiled executable) you would need to write a wrapper function - either as a shell function or an executable script located ahead of the original executable in your PATH. It would need to:

• parse the command line arguments
• intercept your additional option (and any option-specific argument)
• perform the new action
• otherwise pass the remaining arguments to the original command

However your seq should already have an option to specify the number format, which may be (ab)used to get the kind of list you want

   -f, --format=FORMAT
          use printf style floating-point FORMAT

Ex.

$ seq -f 'Item %.0f' 1 10
Item 1
Item 2
Item 3
Item 4
Item 5
Item 6
Item 7
Item 8
Item 9
Item 10

More generally, you could use printf e.g. printf 'Item %d\n' $(seq 1 100) or (using bash's built-in brace expansion) printf 'Item %d\n' {1..100}

BTW rm does have a sort of dry-run flag, -i

-i     prompt before every removal

or (less portably)

-I     prompt once before removing  more  than  three  files,  or  when
      removing recursively; less intrusive than -i, while still giving
      protection against most mistakes