How to use a while loop in shell scripting to print on the same line

Question

Hello i am trying to create a shell script in bash that will print a box with a height and width given by the user. so far my code looks like this

#!/bin/bash 
read height
read width
if [ $height -le 2 ];then
echo "error"
fi
if [ $width -le 2 ];then
echo "error"
fi
#this is where i need help
if [ $height -gt 1];then
   if [ $width -gt 1];then
      echo "+"
      counter=$width
      until [ $counter == 0 ]
   do 
      echo "-"
      let counter-=1
   done
fi
fi

Currently it will print each "-" on a new line, how do i print them on the same line? Thank you

Use printf "%s" "+" etc to print without a newline. Or optionally omit the format string since you're only printing a single character. You'll also need to use loops properly. It could be for ((i = 0; i < height; i++); do for ((j = 0; j < width; j++)); do ...; done; printf '\n'; done — Jonathan Leffler
– Jonathan Leffler, Commented Oct 4, 2017 at 1:00
sorry to clarify my box will be empty on the inside, but with | as the character to make the length part of the box. — Soda
– Soda, Commented Oct 4, 2017 at 1:09
It's a good idea to show what you want as the output in the question — show the input (the height and width you enter) and the corresponding output. A blank interior makes it easier — you can persuade printf to generate spaces. It is harder to make it produce a different fill character. — Jonathan Leffler
– Jonathan Leffler, Commented Oct 4, 2017 at 2:55

Duc Filan · Accepted Answer · 2017-10-04 01:22:13Z

4

Try using printf instead:

printf "-"

To pass arguments during running script, using:

$./shell-script-name.sh argument1 argument2 argument3

Then argument1, argument2 and argument3 becomes $1, $2 and $3 respectively inside your shell script.

In your case:

#!/bin/bash 
height=$1
width=$2
# ... The rest of the file ...

edited Oct 4, 2017 at 1:22

answered Oct 4, 2017 at 1:00

Duc Filan

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8 Comments

Jonathan Leffler Over a year ago

I agree this is part of the answer. The code looks like it needs help with the loops too.

Soda Over a year ago

they might i am new to shell scripting and this is our first assignment for it. so far a while loop seemed the best way to do it. also echo -n '-' ended up working as well.

Soda Over a year ago

follow up question, if i wanted the input to be entered in the command line instead of during the script how would i read and assign them height and width? thank you again

Soda Over a year ago

so to clarify if i just put height (newline) width, when launching $./shell-script-name.sh 10 5 this will set height to 10 and width to 5?

Duc Filan Over a year ago

Inside your shell content, you have to assign height=$1 and then width=$2 before using height and width

|

agc · Accepted Answer · 2017-10-04 03:55:45Z

1

Less overhead than printf is: echo -n "-"

Example:

for f in {1..10} ; do echo -n - ; done ; echo

Output is 10 hyphens:

----------

answered Oct 4, 2017 at 3:55

agc

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