Linux cheasheet

1 minute read

Pass result of awk into kill or another command

docker ps -a | grep houston | awk '{print $1}' | xargs docker rm

Search replace =enforcing to =permissive in file

sudo sed -i 's\=enforcing\=permissive\g' /etc/sysconfig/selinux

Get public key for example to https://google.com

$ openssl s_client -connect google.com:443 | openssl x509 -pubkey -noout

Timestamp to hours since start day

awk '$3/3600000-int($3/86400000)*24+3<13 {print $3, $2, $4}'

  1. /3600000 - unix time in hours units.
  2. /86400000 - unix time in days units.
  3. *24 - start of today in hours units.
  4. +3 - increase 3 hours to align to our timezone.

TCPDUMP Textual

tcpdump -A -iany port 8080 -w scoring-conf-req.tcpdump

Which process listens on port

lsof -n -i:4888 | grep LISTEN

-n causes it to run much faster (do not resolve host names)

iptables

/etc/sysconfig/iptables (iptables configuration)

allow remote connections to port 8140

-A INPUT -m state --state NEW -m tcp -p tcp --dport 8140 -j ACCEPT

  • -A: We are appending a rule.
  • INPUT: The rule applies to incoming packets.
  • -m tcp -p tcp --dport 8140: The rule applies to tcp port 8140.
  • ACCEPT: iptables should accept the packets.

reload iptables

sudo service iptables restart

list processes listening on sockets

netstat -tlp

l: listening p: show process id.

Show users::groups in system

cat /etc/group

clipboard with commandline

pbcopy < ~/.ssh/id_rsa.pub
pbpaste > main.go

push pop directories

pushd ~/tmp; popd

background processes instead of tabs

ctrl-z # suspend process to background
jobs -l # list background
bg
fg
disown -h # disconnect from my user so when I terminate terminal I wont have it.

￿Installing local yum repository on centos 7

yum install vsftpd # => very secure ftpd.

systemctl enable vsftpd # => enable sftpd service.
systemctl start vsftpd # => start sftpd service.

yum install createrepo # => for creation of local repository.

mkdir /var/ftp/pub/localrepo # => this is where our local repo is.

cp -ar /mnt/Packages/*.* /var/ftp/pub/localrepo/ # => copy an existing repo to your localrepo.

vi /etc/yum.repos.d/localrepo.repo # => point to the local repo.

https://www.unixmen.com/setup-local-yum-repository-centos-7/

resources

  1. mastering bash and terminal
  2. bash cheatsheet

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