CentOS

yum install deltarpm (for slow connection ; please first install that rpm)
tcpdump net-tools lsof wget curl telnet nmap rsync ntp iptables-ser\* sysstat vim-enhan\* wireshark traceroute iotop mailx unzip bind-utils epel-rele\* lsync\* httpd-tools\* vnstat\* yum-plugin-verify rng-tools ssldump sshuttle lrzsz strace pip glances tree multitail

top -p `pidof sshd|sed 's/\s/,/g'`
top -p `pgrep -d, -f pl$` ( find perl scripts in f5 )
top -p `pgrep -f myscript.php`
ps -fp $(pgrep -d, -f pid)

grep -m1 root /etc/passwd
Ctrl+S (XOFF)
Ctrl+Q (XON)


ls -d */
find /etc -type f -name \* -size 0


timedatectl set-timezone Asia/Rangoon
hostnamectl set-hostname
nmtui edit ens160
nmcli con add con-name ens160 ifname ens160 type ethernet ip4 192.168.241.23/24 gw4 192.168.241.1
yum install epel\*
yum erase rsyslog
yum install epel-release
yum repolist
yum check-update

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netstat -lnp -A inet
openssl s_client -connect exmaple.com:443 |openssl x509 -noout -dates
openssl s_client -connect exmaple.com:443 |openssl x509 -text
cat testtext.txt |awk '{if($1 =="#"){print $0} else {print $5,$6}}'
gpg --list-keys
gpg --list-secret-keys
gpg -d <filename.gpg> (If there are multiple keys, it will automatically choose the correct one.)
################
lvs
df -h
df -i
find /shared/ -xdev -type f -exec du {} \; | sort -rn | head -20
find /var -type f -size +100M -exec ls -lh {} \;
dd if=/dev/zero of=10mbfile bs=1MB count=10
:Ex - open in current window
:Vex - opens a new vertical window
:Sex - open a new horizinal window
netstat -lnp -A inet
test f5 direcotry
http://stackoverflow.com/questions/12120935/wget-output-document-and-headers-to-stdout
http://blog.mailgun.com/25-465-587-what-port-should-i-use/
echo -ne "OXYugGKg207g5uN/07V" | xxd -plain | tr -d '\n' | sed 's/\(..\)/%\1/g'