From this reddit survey, https://redd.it/4a2pjq, I find our fellow linux sysadmin use the following tools have a look in this list that I have compiled

packer: For creating the universal images

lftp: for client file transfer

pidgin: universal chat client

fpm: To create own packages

screen:

dd:

asciidoc:

dig:

tcpdump

rsync/rdiff-backup

ipython, terraform, vscode, dstat,

grep, tail, du, df

find

puppet

vim-arline

syntastic

itop

pv

zabbix

awk

yakuake

netcat

geany

cssh, clusterssh, geppetto

Newrelic

keypassX

slack

CopyQ

meld

git

sublime3

ansible

nginx

haproxy

iptables

postgresql

redis

varnish

rsnapshot

terraform

awi-cls

iptables

python

ettercap

netcat/socat/crytcat

Twiki

openvpn

asterisk

pdsh

masscan

srun

sbatch

sacct

squeue

qstat

checkjob

scontrol

sinfo

showq

lua

qsb

horcm

saltstack

remmina

syncthing

Nedi

zsh

edkiga zoiper