用于递减传递的参数的Shell脚本

Question

So I was working on a project tonight and assumed based on my poor understanding that the requirement was to create a script to take a number and count down to 1 with commas on the same line.

A few people here introduced me to the seq command and I was on my way.

Turns out it needs to take the variable integer from a command line argument.

What I have now:

#!/bin/bash
#countdown

read -p "Enter a Number great than 1: " counter

seq -s, $counter -1 

Needs to work by taking an argument after the line, such as /assign1p1 5 and then outputting 5,4,3,2,1

I've seen the $1 used as an argument marker? Is that how to work from it?

Answer 1

Use Three Arguments

The correct call to seq for your use case is:

seq [OPTION]... FIRST INCREMENT LAST

To decrement your starting value down to 1 using the defined separator, try something similar to this example:

$ set -- 5
$ seq -s, $1 -1 1
5,4,3,2,1

Obviously, the call to set won't be needed inside the script, but is a great way to test at the command line.

Answer 2

The command-line arguments passed to your script are $1 , $2 , etc.

#!/bin/bash

seq -s, $1 1
echo

If you want to make this more robust you might want to verify that the user passed in the correct number of arguments, which is the variable $# .

#!/bin/bash

if (( $# != 1 )); then
    echo "Usage: $0 num" >&2
    exit 1
fi

seq -s, $1 1
echo

Answer 3

Arguments passed to the script from the command line include : $0, $1, $2, $3 . . .

$0 is the name of the script itself, $1 is the first argument, $2 the second, $3 the third, and so forth. [2] After $9, the arguments must be enclosed in brackets, for example, ${10}, ${11}, ${12}.

Answer 4

If for whatever reason you do not want to use seq

a=$1
for (( b = a; b > 0; b-- ))
do
  (( b == a )) || printf ,
  printf $b
done