List all processes and how much swap they use.

lsswap

#!/bin/bash
#
# Riyad Preukschas <riyad@informatik.uni-bremen.de>
# License: Mozilla Public License 2.0
# SPDX-License-Identifier: MPL-2.0
#
# List all processes and how much swap they use.
# The output format is: "<swap used> : <pid> : <process name>"
#
# To get the top 10 processes using swap you can run:
# lsswap | sort -hr | head -n10

files=(/proc/*/status)
exec awk '
    BEGINFILE {
        # skip files that cannot be opened
        if ( ERRNO != "" ) {
            nextfile
        }
    }
    /^VmSwap:/ {
        vmswap = $2;
        vmswap_unit = $3;

        # force conversion to a number
        vmswap += 0

        # make units more human readable
        if (vmswap_unit == "kB" && vmswap > 1000) {
            vmswap /= 1000
            vmswap_unit = "MB"
        }
        if (vmswap_unit == "MB" && vmswap > 1000) {
            vmswap /= 1000
            vmswap_unit = "GB"
        }
    }
    /^Name:/   { name = $2 }
    /^Pid:/    { pid = $2 }
    ENDFILE {
        # skip processes that cannot be swapped or are not using swap at all
        if (length(vmswap) != 0 && vmswap != 0) {
            printf "%1.1f%s : %d : %s\n", vmswap, vmswap_unit, pid, name
        }
    }
' "${files[@]}"