I came here looking for a solution to the same problem. It's surprising there isn't yet a better answer for this. I created my own slightly more flexible fix based on this thread and other pages I read on the web.

I to make things more human readable I made an auto ranging function and used that on the vsz and rss fields.

Also, it looks like there IS actually a way to force an arbitrary field separator on ps. Here is how I did it:

Since I was processing the output with awk which can handle multi-character field separators, I used zzz:::zzz% as my field separator. To do this I have to pass zzz:::zzz%% to ps (note the extra % at the end). See my examples below.

|head -n20 and |cut -c -250 at the end is to limit the output to 20 lines and cut each line after 250 characters to keep things neat for my terminal. For actual scripting purposes you would likely want to remove these.

EDIT: I added a variable to call out the fact that you can also sort by any field using these examples. The names for the fields can be found in the manpage for ps under the heading STANDARD FORMAT SPECIFIERS

EXAMPLE 1

sortbyfield="rss"; fsep="-o "zzz:::zzz%%" -o"; ps ax o user:16 $fsep pid $fsep pcpu $fsep pmem $fsep vsz $fsep rss $fsep tty $fsep stat $fsep lstart $fsep time:16 $fsep cmd --sort -$sortbyfield | awk 'function setprefix(num){{n_suffix=1; while(num > 1000 && n_suffix < suffixes_len) {num /= 1024; n_suffix++;}; num=int(100*num)/100suffixes[n_suffix]}; return num} BEGIN{suffixes_len=split("kB MB GB TB PB EB ZB",suffixes);FS="zzz:::zzz%";} NR>1 {$5=setprefix($5);$6=setprefix($6); }{ printf "%-16s %6s %-5s %-5s %9s %9s %-8s %-8s %-25s %-18s %s\n", $1, $2, $3, $4, $5, $6, $7, $8, $9, $10, $11;}' |head -n20 |cut -c -250 

OUTPUT: (slightly sanitized example)

USER PID %CPU %MEM VSZ RSS TT STAT STARTED TIME CMD gdm 1474 0.0 0.3 2.87GB 182.86MB tty1 Sl+ Sat Jun 18 01:31:44 2022 00:34:40 /usr/bin/gnome-shell gdm 1370 0.0 0.0 171.3MB 34.31MB tty1 Sl+ Sat Jun 18 01:31:43 2022 00:01:56 /usr/libexec/Xorg vt1 -displayfd 3 -auth /run/user/42/gdm/Xauthority -background none -noreset -keeptty -verbose 3 gdm 1552 0.0 0.0 686.07MB 20.14MB tty1 Sl+ Sat Jun 18 01:31:46 2022 00:00:40 /usr/libexec/gsd-color gdm 1577 0.0 0.0 870.49MB 19.53MB tty1 Sl+ Sat Jun 18 01:31:46 2022 00:00:01 /usr/libexec/gsd-media-keys gdm 1538 0.0 0.0 531.81MB 18.51MB tty1 Sl+ Sat Jun 18 01:31:46 2022 00:00:00 /usr/libexec/gsd-xsettings gdm 1541 0.0 0.0 539.53MB 18.5MB tty1 Sl+ Sat Jun 18 01:31:46 2022 00:00:04 /usr/libexec/gsd-power gdm 1570 0.0 0.0 458.5MB 18.4MB tty1 Sl+ Sat Jun 18 01:31:46 2022 00:00:00 /usr/libexec/gsd-wacom gdm 1500 0.0 0.0 386.57MB 17.94MB tty1 Sl Sat Jun 18 01:31:45 2022 00:00:00 /usr/libexec/ibus-x11 --kill-daemon gdm 1537 0.0 0.0 386.13MB 17.92MB tty1 Sl+ Sat Jun 18 01:31:46 2022 00:00:00 /usr/libexec/gsd-clipboard 

EXAMPLE 2

Slightly less verbose version:

sortbyfield="rss"; fsep="-o "zzz:::zzz%%" -o"; ps ax o user:16 $fsep pid $fsep pcpu $fsep pmem $fsep vsz $fsep rss $fsep tty $fsep stat $fsep lstart $fsep time:16 $fsep comm --sort -$sortbyfield | awk 'function setprefix(num){{n_suffix=1; while(num > 1000 && n_suffix < suffixes_len) {num /= 1024; n_suffix++;}; num=int(100*num)/100suffixes[n_suffix]}; return num} BEGIN{suffixes_len=split("kB MB GB TB PB EB ZB",suffixes);FS="zzz:::zzz%";} NR>1 {$5=setprefix($5);$6=setprefix($6); }{ printf "%-16s %6s %-5s %-5s %9s %9s %-8s %-8s %-25s %-18s %s\n", $1, $2, $3, $4, $5, $6, $7, $8, $9, $10, $11;}' |head -n20 |cut -c -250 

OUTPUT: (slightly sanitized example)

USER PID %CPU %MEM VSZ RSS TT STAT STARTED TIME COMMAND gdm 1474 0.0 0.3 2.87GB 182.86MB tty1 Sl+ Sat Jun 18 01:31:44 2022 00:34:40 gnome-shell gdm 1370 0.0 0.0 171.3MB 34.31MB tty1 Sl+ Sat Jun 18 01:31:43 2022 00:01:56 Xorg gdm 1552 0.0 0.0 686.07MB 20.14MB tty1 Sl+ Sat Jun 18 01:31:46 2022 00:00:40 gsd-color gdm 1577 0.0 0.0 870.49MB 19.53MB tty1 Sl+ Sat Jun 18 01:31:46 2022 00:00:01 gsd-media-keys gdm 1538 0.0 0.0 531.81MB 18.51MB tty1 Sl+ Sat Jun 18 01:31:46 2022 00:00:00 gsd-xsettings gdm 1541 0.0 0.0 539.53MB 18.5MB tty1 Sl+ Sat Jun 18 01:31:46 2022 00:00:04 gsd-power gdm 1570 0.0 0.0 458.5MB 18.4MB tty1 Sl+ Sat Jun 18 01:31:46 2022 00:00:00 gsd-wacom gdm 1500 0.0 0.0 386.57MB 17.94MB tty1 Sl Sat Jun 18 01:31:45 2022 00:00:00 ibus-x11 gdm 1537 0.0 0.0 386.13MB 17.92MB tty1 Sl+ Sat Jun 18 01:31:46 2022 00:00:00 gsd-clipboard 

Hopefully this helps someone out there!