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How would I create a bash script that the user can use to sum any amount of command line arguments, but it will also ignore incompatible arguments? For example, say my script is called sum:

sum 10 -argument1 -argument2 -argument3 20

30

sum 7 -argument1 2 -argument2 1 -argument3

10

With awk, assuming the sum and each individual number argument can fit in your system's long type, and only considering sequences of decimal digits with an optional leading - sign:

#! /bin/sh -

awk 'BEGIN{

  sum = 0

  for (i = 1; i < ARGC; i++)

    if (ARGV[i] ~ /^-?[0123456789]+$/)

      sum += ARGV[i]

  print sum}' "$@"

For arbitrary precision, you can use bc:

#! /bin/sh -

awk 'BEGIN{

  for (i = 1; i < ARGC; i++)

    if (ARGV[i] ~ /^-?[0123456789]+$/)

      print "s+="ARGV[i]

  print "s"}' "$@" | bc

Example:

$ ./sum1 999999999999999999999999 1

999999999999999983222784

$ ./sum2 999999999999999999999999 1

1000000000000000000000000

One (nonoptimal) example to do the sum:

echo "$@" |awk '{for (i = 1; i <= NF; i++) j+=$i} END {print j}'

(assuming number is everything awk accept as such)

Example:

./ff 1 2 3.1   0x10 0100

86.1

And warning: any word which start with number will be interpreted as number

Here's another possibility

printf "%sn" "$@" | awk '$1 ~ /^[[:digit:]]+$/ {s+=$1} END {print s}'

It takes each argument from the command line and prints it, one per line. The awk script accepts this data and adds up non-zero positive values, printing the result when it's received all the data

Example

#!/bin/sh

printf "%sn" "$@" | awk '$1 ~ /^[[:digit:]]+$/ {s+=$1} END {print s}'



./sum 1 -argument2 2 -argument4 3

6

If you could guarantee that your numeric arguments contained only digits you could simplify the check expression from $1 ~ /^[[:digit:]]+$/ to $1+0 > 0.