How to output an array's content in columns in BASH.

Question

I wanted to display a long list of strings from an array.

Right now, my script run through a for loop echoing each value to the standard output:

for value in ${values[@]}
do
  echo $value
done

Yeah, that's pretty ugly! And the one column listing is pretty long too...

I was wondering if i can find a command or builtin helping me to display all those values in columns, like the ls command does by default when listing a directory (ls -C).

[Update]

Losing my brain with column not displaying properly formatted columns, here's more info:

The values: $ values=( 01----7 02----7 03-----8 04----7 05-----8 06-----8 07-----8 08-----8 09---6 10----7 11----7 12----7 13----7 14-----8 15-----8 16----7 17----7 18---6 19-----8 20-----8 21-----8) (Notice the first two digits as an index and the last one indicating the string length for readability)

The command: echo " ${values[@]/%/$'\n'}" | column

The result:

Something is going wrong...

Answer 1

Tabspaces

---

Use a tab after each value.

( It automatically flows to next line too... )

for value in ${values[@]}
do
  echo -en "$value\t"
done

Detailed info here

GoodLUCK!!
- CVS

Answer 2

You could pipe your output to column.

column seems to struggle with some data in a single-column input being narrower than a tabstop (8 characters). Using a for-loop, padding to 8 characterss seems to do the trick:

for item in "${values[@]}"; do 
    printf "%-8s\n" "${item}"
done | column

Answer 3

Here are a couple of techniques that can be used with Johnsyweb's answer so you can do your output without a loop:

saveIFS=$IFS
IFS=$'\n'
echo "${values[*]}" | column
IFS=$saveIFS

or

echo " ${arr[@]/%/$'\n'}" | column

or

echo " ${arr[@]/%/$'\n'}" | sed 's/^ //' | column

Answer 4

It may look overkill, but i came up with my own solution. I wrote a little script that does exactly what i wanted: take a list of values and output them in a pretty formatted column view.

http://github.com/Arko/Columnize