mjhjmtu

fold can wrap the line if it has more than a certain amount of characters. However, I want to wrap a text file which has less than 40 characters in each line into two columns (80 chars per line total).

I want to make

apple
banana
(28 items omitted)
grape
guava

into

apple ...
banana ...
(12 items omitted) (12 items omitted)
... grape
... guava

How can I make it?

Using the -COLUMN or --columns=COLUMN option of pr

-COLUMN, --columns=COLUMN
 output COLUMN columns and print columns down, unless -a is used.
 Balance number of lines in the columns on each page

so either

pr -t -2 yourfile

or

pr -t --columns=2 yourfile

For example, augmenting your entries with some random dictionary words,

$ cat << EOF | pr -t -2
> apple
> banana
> `shuf -n28 /usr/share/dict/words`
> grape
> guava
> EOF
apple overachieves
banana wickerwork
cottonmouths supersonic
adapter's draftiest
boudoir's insisting
cruised programs
mousetrap parcel
shticks basically
TLC's coruscates
conduction Jones
geeing Ty
gloamings bondage
investing candelabra's
radiotherapists Inchon's
clasp's grape
critters guava

You can use the columns command from the autogen package, e.g.:

columns -c 2 -w 40 --by-column < input

For example:

 echo apple
 echo banana
 shuf -n28 /usr/share/dict/words
 echo grape
 echo guave
 |
columns -w 40 -c 2 --by-columns

Output:

apple merwoman
banana chiroplasty
antispreading stylommatophorous
spearmint Sphaerobolaceae
sulphoxyphosphate snark
nymphaeum reactionary
ahluwalia hobo
husky oxamethane
crimeproof deltarium
cerebrosis hematoporphyrin
yoghurt noncompoundable
colloquial sororially
unaffirmed nonobjection
saccharated reundercut
thermochemic grape
preobedience guave

Adding to Steeldriver's answer, if you have a requirement like mine, i.e. to print alternate words in same columns, use -a(across) option.

[user@server ~]$ cat << EOF | pr -a -t -2
> word1
> word2
> word3
> word4
> word5
> word6
> EOF
word1 word2
word3 word4
word5 word6