sort -t, -nk3 user.csv

donde:

-t, - define que el delimitador es la ,.

-n - brinda el ordenamiento numerico.

-k3 - define que columna usará para ordenamiento.

% Cortar del final
# cortar del inicio

#!/bin/bash
IMAGEN="$1"
EXTENSION="${IMAGEN##*.}"

images=pasdasd.jpg
echo ${images##*.}
echo ${images%.*}
I="cn=lisa,dc=example,dc=com"
echo ${I##*=}
echo ${I%%=*}
ACTUAL=$(xrandr | grep current | cut -d "," -f 2)
RenX=$(echo $ACTUAL | cut -d " " -f 2)
RenY=$(echo $ACTUAL | cut -d " " -f 4)
echo ${RenX}
echo ${RenY}

Referencias

https://www.linux.com/tutorials/all-about-curly-braces-bash/

https://devhints.io/bash

https://www.linuxjournal.com/content/bash-brace-expansion

https://www.lifewire.com/test-linux-command-unix-command-4097166

https://stackoverflow.com/questions/17048188/how-to-use-awk-sort-by-column-3