Question

Is there a *nix command that formats input (delimited by newlines) so that only a specific max number of elements appear per line? For example:

$ yes x | head -10 | command 4
x x x x
x x x x
x x

I wrote a quick bash script (shown below) that performs this task, but it seems long and probably inefficient. Is there a better way to do this?

#!/bin/sh

if [ -z "$1" -o -z "$2" ]; then
        echo Usage `basename $0` {rows} {columns}
        exit 1
fi

ROWS=$1
COLS=$2

input=$(yes x | head -${ROWS})
lines=()
i=0
j=0
eol=0

for x in ${input[*]}
do
        lines[$i]="${lines[$i]} $x"
        j=`expr $j + 1`
        eol=0
        if [ $j -ge ${COLS} ]; then
                echo lines[$i] = ${lines[$i]}
                i=`expr $i + 1`
                j=0
                eol=1
        fi
done

if [ ${eol} -eq 0 ]; then
        echo lines[$i] = ${lines[$i]}
fi

Answer 1

printf '%-10s%-10s%-10s%s\n' $(command | command)

printf will consume the number of arguments specified in the format string at a time and continue until they’re all consumed.

Demonstration:

$ printf '%-10s%-10s%-10s%s\n' $(yes x | head -n 10)
x         x         x         x
x         x         x         x
x         x
$ printf '%-10s%-10s%-10s%s\n' $(<speech)
now       is        the       time
for       all       good      men
to        come      to        the
aid       of        their     country