Can I use 'column' in bash where a column has a newline? - bash

Question

Suppose I have an associative array of ( [name]="Some description" ).
declare -A myItems=(
[item1]='Item1 description'
[item2]='Item2 description'
)
I now want to print a table of myItems with nice, even column lengths.
str=''
for n in $(echo "${!myItems[#]}" | tr " " "\n" | sort); do
str+="$n\t${myItems[$n]}\n"
done
# $(printf '\t') was the simplest way I could find to capture a tab character
echo -e "$str" | column -t -s "$(printf '\t')"
### PRINTS ###
item1 Item1 description
item2 Item2 description
Cool. This works nicely.
Now suppose an item has a description that is multiple lines.
myItems=(
[item1]='Item1 description'
[item2]='Item2 description'
[item3]='This item has
multiple lines
in it'
)
Now running my script prints
item1 Item1 description
item2 Item2 description
item3 This item has
multiple lines
in it
What I want is
item1 Item1 description
item2 Item2 description
item3 This item has
multiple lines
in it
Is this achievable with column? If not, can I achieve it through some other means?

Answer 1

Assuming the array keys are always single lines, you can prefix all newline characters inside the values by a tab so that column aligns them correctly.
By the way: Bash supports so called C-Strings which allow you to specify tabs and newlines by their escape sequences. $'\n\t' is a newline followed by a tab.
for key in "${!myItems[#]}"; do
printf '_%s\t%s\n' "$key" "${myItems[$key]//$'\n'/$'\n_\t'}"
done |
column -ts $'\t' |
sed 's/^_/ /'
If you also want to sort the keys as in your question, I'd suggest something more robust than for ... in $(echo ...), for instance
printf %s\\n "${!myItems[#]}" | sort |
while IFS= read -r key; do
...
And here is a general solution allowing for multi-line keys and values:
printf %s\\0 "${!myItems[#]}" | sort -z |
while IFS= read -rd '' key; do
paste <(printf %s "$key") <(printf %s "${myItems[$key]}")
done |
sed 's/^/_/' | column -ts $'\t' | sed 's/^_//'

Answer 2

You may use this 2 pass code:
# find max length of key
for i in "${!myItems[#]}"; do ((${#i} > max)) && max=${#i}; done
# create a variable filled with space using max+4; assuming 4 is tab space size
printf -v spcs "%*s" $((max+4)) " "
# finally print key and value using max and spcs filler
for i in "${!myItems[#]}"; do
printf '%-*s\t%s\n' $max "$i" "${myItems[$i]//$'\n'/$'\n'$spcs}"
done
item1 Item1 description
item2 Item2 description
item3 This item has
multiple lines
in it

Answer 3

Something tested
#!/usr/bin/env bash
declare -A myItems=(
[item1]='Item1 description'
[item2]='Item2 description'
[item3]='This item has
multiple lines
in it'
)
# Iterate each item by key
for item in "${!myItems[#]}"; do
# Transform lines of item name into an array
IFS=$'\n' read -r -d '' -a itemName <<<"$item"
# Transform lines of item description into an array
IFS=$'\n' read -r -d '' -a itemDesc <<<"${myItems[$item]}"
# Computes the biggest number of lines
lines=$((${#itemName[#]}>${#itemDesc[#]}?${#itemName[#]}:${#itemDesc[#]}))
# Print each line formated
for (( l=0; l<lines; l++)); do
printf '%-8s%s\n' "${itemName[$l]}" "${itemDesc[$l]}"
done
done
Output:
item1 Item1 description
item2 Item2 description
item3 This item has
multiple lines
in it