How I can print the content of an array in columns ands rows

Question

Im pretty new to bash but im trying to learning. My question is:

Im running this ps to get the info and sending to /tmp/freememory.txt

#!/bin/bash
ps -eo pid,ppid,cmd,%mem,%cpu --sort=-%mem | head >/tmp/freememory.txt

cat   "/tmp/freememory.txt"

the output is

PID      PPID CMD                         %MEM %CPU
  859     1 /usr/lib/snapd/snapd         1.3  0.0
  890     1 /usr/bin/python3 /usr/share  0.9  0.0
  845     1 /usr/bin/python3 /usr/bin/n  0.8  0.0
  851     1 /usr/sbin/NetworkManager --  0.8  0.0
  300     1 /lib/systemd/systemd-journa  0.7  0.0
 1501     1 /usr/lib/packagekit/package  0.6  0.0
  996     1 /usr/bin/whoopsie -f         0.6  0.0
 3530     1 /usr/sbin/cups-browsed       0.5  0.0
  855     1 /usr/sbin/ModemManager --fi  0.4  0.0

Im learning arrays,so my idea is to create an array to show the same ouput:

ARRAY= (cat /tmp/freememory.txt)


echo ${ARRAY[@]}

But the output difficult to read

PID PPID CMD %MEM %CPU 859 1 /usr/lib/snapd/snapd 1.3 0.0 890 1 /usr/bin/python3 /usr/share 0.9 0.0 845 1 /usr/bin/python3 /usr/bin/n 0.8 0.0 851 1 /usr/sbin/NetworkManager -- 0.8 0.0 300 1 /lib/systemd/systemd-journa 0.7 0.0 1501 1 /usr/lib/packagekit/package 0.6 0.0 996 1 /usr/bin/whoopsie -f 0.6 0.0 3530 1 /usr/sbin/cups-browsed 0.5 0.0 855 1 /usr/sbin/ModemManager --fi 0.4 0.0

Its ther any way that the array output looks like the first output from(cat "/tmp/freememory.txt")?

Thanks

Answer 1

The bash shell only really supports 1d arrays - if you are content with an array of lines that's simple enough using the mapfile (aka readarray) builtin:

$ mapfile -t array < freememory.txt

$ printf '%s\n' "${array[@]}"
PID      PPID CMD                         %MEM %CPU
  859     1 /usr/lib/snapd/snapd         1.3  0.0
  890     1 /usr/bin/python3 /usr/share  0.9  0.0
  845     1 /usr/bin/python3 /usr/bin/n  0.8  0.0
  851     1 /usr/sbin/NetworkManager --  0.8  0.0
  300     1 /lib/systemd/systemd-journa  0.7  0.0
 1501     1 /usr/lib/packagekit/package  0.6  0.0
  996     1 /usr/bin/whoopsie -f         0.6  0.0
 3530     1 /usr/sbin/cups-browsed       0.5  0.0
  855     1 /usr/sbin/ModemManager --fi  0.4  0.0

Note the double quotes around "${array[@]}" to prevent word splitting. You can skip the file and read into the array directly from the ps pipeline if you prefer, using process substitution:

mapfile -t array < <(ps -eo pid,ppid,cmd,%mem,%cpu --sort=-%mem | head)