ulimit -a
# 使用netstat 命令查看连接数
netstat -n | awk '/^tcp/ {++state[$NF]} END {for(key in state) print key,"t",state[key]}'
# 查看网络状态
sar -n DEV 1
# 查看IO状态
iostat 1
# 查看cpu状态
mpstat -P ALL
# 查看22端口链接
ss -lntup |grep 22
ss -tunl | grep 6443
netstat -lntup |grep 22
# 查找文件
find *.md | xargs grep -ri "ch"

tmux
screen
tree
dirs
pushd
popd
locate
iftop
percol
fasd
sed
awk
perl
htop
grep
awk
sed
cat
find
which
xargs
lsof
netstat
iotop
iftop
apg
`locate / | fzf -m`
fish
ag
cloc
dtrx
aunpack
less
sdcv
httpie
jq
expect
traceroute -> mtr / mtr-tiny
top -> htop
tmux -> byobu
sysvinit -> systemd 
bash -> zsh + oh-my-zsh 
cd -> popd
apt-get -> aptitude
scp -> rsync
grep - > ack
ncdu - > du
ls - >exa
watch -n 1 -d netstat -lnp
df - > pydf
net-tools - > iproute2
iptables - > nftables
{i，} python - > ptipython
df - > dfc