How to add an unknown amount of numbers from user input in Linux shell script

Question

I'm trying to add up all numbers inputted by a user, however there is no limit on how many numbers a user can input for the addition. How do I code this in linux shell script?

I have this so far:

firstNumber=0
secondNumber=0
number=0


echo Please enter two numbers to add up

read firstNumber
read secondNumber

echo Would you like to keep adding numbers? YES OR NO
read answer

if answer = YES
then
echo Please add another number
read number
echo $(($firstNumber +$secondNumber + $number))
fi

while answer = NO
do
echo $(($firstNumber + $secondNumber))
done

@Loïc I'm trying to loop through input information and store it in the sum but it's not really working — help
– help, Commented Nov 29, 2019 at 13:12
sounds like a good start, please show your code (edit your question) — Loïc
– Loïc, Commented Nov 29, 2019 at 13:12
You might want to rephrase the problem: sum up a list of numbers from the user, the user will flag the end of the list with empty line (or some other value). This will be easier on the user (less typing), and save you testing time — dash-o
– dash-o, Commented Nov 29, 2019 at 13:25
It is not clear what the problem is. What is the problem? Also see How to use Shellcheck, How to debug a bash script? (U&L.SE), How to debug a bash script? (SO), How to debug bash script? (AskU), Debugging Bash scripts, etc. — jww
– jww, Commented Nov 29, 2019 at 14:56

7 revs · Accepted Answer · 2019-11-29 15:15:37Z

as @dash-o recommended, a simple entry sequence ended with ENTER is the most simple approach:

#!/usr/bin/env sh

sum=0

echo "Please enter integer numbers to add, or just RETURN to end."

while read -r number && [ -n "$number" ]; do
  if [ "$number" -eq "$number" ] 2>/dev/null; then
    sum=$((sum + number))
    echo "Sum is: $sum"
  else
    echo "$number is not a valid integer. Try again..." >&2
  fi
done

Or to allow multiple integers entry per line:

#!/usr/bin/env sh

# Save the shell's options state
shelloptions="$(set +o)"
# Disable globbing to prevent filename expansion in parameters
set -o noglob

sum=0

echo "Please enter integer numbers to add, or RETURN to end."

# Read lines until empty REPLY
while read -r && [ -n "$REPLY" ]; do

  # Split $REPLY as parameters
  # Globbing is turned-off so filenames will not mess with entries
  # shellcheck disable=SC2086 # Explicitly intended word splitting
  set -- $REPLY

  # Iterate numbers from the parameters array
  for number in "$@"; do

    # If $number is a valid integer
    if [ "$number" -eq "$number" ] 2>/dev/null; then
      sum=$((sum + number))
    else
      echo "$number is not a valid integer." >&2
    fi
  done
  echo "Sum is: $sum"
done

# Restore the shell's options state
eval "$shelloptions"

Dmitry Zaitsev · Accepted Answer · 2024-09-25 18:29:43Z

Having a list of students, one student in a line, you can add/delete them (including home directories). There can be many words in a line, though I treat the first word as a name and the last word as a surname. I use their concatenation as a username and their reverse order concatenation as a default password. If you export a file from Windows, please be sure you corrected ends of lines with dos2linux. Just run:

sudo ./add-usr-script stud-list.txt

# creates (deletes) users on a list ($1) 
# using the first (n) and the last (s) word of each line

cat $1 | while read line 
do
  echo $line
  s=${line##* }
  n=${line%% *}
  pw="${s}${n}"
  un="${n}${s}"
  pass=$(perl -e 'print crypt($ARGV[0], "password")' $pw)
  useradd -m -p "$pass" "$un"  
# userdel "$un"
# rm -r "/home/${un}"
  echo user: "$un" passwd: "$pw" encrypted_passwd: "$pass"
done

Collectives™ on Stack Overflow

How to add an unknown amount of numbers from user input in Linux shell script

2 Answers 2

Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related