1. Run a script with no output and in the background
$ ./my_script.sh > /dev/null 2>&1 &
2. Run a script with no output and in the background and see the pid
$ ./my_script.sh > /dev/null 2>&1 & echo $!
3. Template script that loops thru and writes to a file
#!/bin/bash
# $1 - number of minutes
# $2 - task id
COUNTER=$(($1*60/5))
TOTAL=$COUNTER
echo Perfload will run for $1 minutes
echo "Perfload will run for $1 minutes" > /tmp/$2.log
until [ $COUNTER -eq 0 ]; do
echo The counter is $COUNTER
PROGRESS=$(echo "scale=2;($TOTAL - $COUNTER)*100/$TOTAL" | bc -l)
echo "Perfload RUNNING $PROGRESS %" >> /tmp/$2.log
let COUNTER-=1
sleep 5
done
echo "Perfload SUCCESS" >> /tmp/$2.log
7.21.2015
Bash Cheat Sheet
7.14.2015
Cisco Switch Cheat Sheet
sho lldp neighbors sho cdp ne switch-name# show mac address-table | i 0060.165c.f83e * 2016 0060.165c.f83e dynamic ~~~ F F Eth1/22 switch-name# sho int description | grep 'yogi34 eth4b' Eth8/19 eth 10G yogi34 eth4b 90E2BA068BB1 switch-name# show interface ethernet 2/27 description ------------------------------------------------------------------------------- Port Type Speed Description ------------------------------------------------------------------------------- Eth2/27 eth 10G artemis59-eth3b 0060.1645.505a switch-name(config)# config switch-name(config)# int e8/19 switch-name(config-if)# inherit port-profile Apposite switch-name(config-if)# exit switch-name(config)# exit switch-name# copy run startup-config switch-name# show interface ethernet 1/28 switchport # If missing VLANs, can set using... switch-name(config-if)# switchport trunk allow vlan 2016,2030-2049
5.15.2015
Configure VLAN tagging via CLI
1. Create VLAN interface
# ip link add link eth4 name eth4.2030 type vlan id 2030
2. Assign IP
# ifconfig eth4.2030 11.0.20.1 netmask 255.255.240.0
3. Make sure new interface is enabled
# ifconfig eth4.2030 up
4. Check
# ifconfig eth4.2030
eth4.2030 Link encap:Ethernet HWaddr 90:E2:BA:6D:B5:95
inet addr:11.0.20.1 Bcast:11.0.31.255 Mask:255.255.240.0
inet6 addr: fe80::92e2:baff:fe6d:b595/64 Scope:Link
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:10 errors:0 dropped:0 overruns:0 frame:0
TX packets:6 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:0
RX bytes:1046 (1.0 KiB) TX bytes:468 (468.0 b)
5. Remove VLAN
# ip link delete eth4.2030
4.29.2015
Sync Clock Automatically on CentOS
Got it from here.
1. Install # yum install ntp ntpdate ntp-doc 2. Turn on service # chkconfig ntpd on 3. Sync one time # ntpdate pool.ntp.org 4. Configure ntpd # vi /etc/ntp.conf Add public servers server 0.rhel.pool.ntp.org server 1.rhel.pool.ntp.org server 2.rhel.pool.ntp.org 5. Start the NTP server. The following will continuously adjusts system time from upstream NTP server. No need to run ntpdate: # /etc/init.d/ntpd start
3.12.2015
Ansible for Configuration Management and IT automation
Wow, Ansible is a great tool for configuration management and IT automation. I got this reference from here and here.
1. Install ansible on your workstation (machine which will be the controller) $ sudo yum install ansible $ ansible --version 2. Create env variable $ export ANSIBLE_HOSTS=~/ansible/ansible_hosts 3. Create hosts file $ echo -e "perf-c690\nperf-c691" > ~/ansible/ansible_hosts 4. Do a quick ping $ ansible all -m ping --ask-pass 5. Now, let's create ssh keys (Should typically run using your own user account, have used root here for convenience) # ssh-keygen -t rsa 6. Copy public key to the remote machines $ ansible all -m copy -a "src=/root/.ssh/id_rsa.pub dest=/tmp/id_rsa.pub" --ask-pass -c paramiko Warning: error message: "Aborting, target uses selinux but python bindings (libselinux-python) aren't installed!" Which means we need to install libselinux-python on the remote machine prior to copying the files there. We can use ansible to do that for us. Install libselinux-python on remote machines $ ansible all -m yum -a "name=libselinux-python state=latest" -u root --ask-pass -c paramiko Now we can go back to copying the public key 7. Let's add the public key to the remote machines $ ansible all -m shell -a "cat /tmp/id_rsa.pub >> /root/.ssh/authorized_keys" --ask-pass -c paramiko 8. Test if we actually don't need any password $ ansible all -m shell -a "hostname" 9. Now we can do or install whatever on the remote machines, let's try installing expect $ ansible all -m yum -a "name=expect state=latest" -u root 10. We can remotely reboot all machines at once $ ansible all -a "/sbin/reboot" -u root
3.10.2015
Install Ruby via RVM on CentOS 6.5
Got install from here.
RVM best practices here.
How to use RVM gemsets here.
How to use Bundler here.
RVM best practices here.
How to use RVM gemsets here.
How to use Bundler here.
1. Install pre-requisites # yum groupinstall -y development 2. Install RVM # curl -L get.rvm.io | bash -s stable 3. Create system environment for RVM # source /etc/profile.d/rvm.sh 4. Install Ruby # rvm reload # rvm install 2.2.1 5. Check version of ruby installed # ruby --version 6. To see all rubies installed # rvm list rubies rvm rubies =* ruby-2.2.1 [ x86_64 ] # => - current # =* - current && default # * - default 7. To set a Ruby version as the default # rvm use 2.2.1 --default Using /usr/local/rvm/gems/ruby-2.2.1 8. Shortcut - create a new gemset along with a fresh .rvmrc in our project directory # cd projects/dev/phoenix # rvm --rvmrc --create use 2.2.1@phoenix ruby-2.2.1 - #gemset created /usr/local/rvm/gems/ruby-2.2.1@phoenix ruby-2.2.1 - #generating phoenix wrappers.......... Using /usr/local/rvm/gems/ruby-2.2.1 with gemset phoenix 9. To ignore rmvrc warnings ... # rvm rvmrc warning ignore all.rvmrcs 10. Now when we cd to our project directory we get a confirmation which ruby-version and gemset we are using... dev]# cd phoenix/ Using: /usr/local/rvm/gems/ruby-2.2.1@phoenix 11. Let's make use of bundler to make it easy to track and install the exact gems and versions for our project # gem install bundler 12. Create a Gemfile # bundle init Writing new Gemfile to /root/projects/dev/phoenix/Gemfile 13. Add gems to Gemfile # vi Gemfile source "https://rubygems.org" # 1. de facto XML/HTML parsing library gem 'nokogiri' 14. Now, let's install all gems we listed in the Gemfile # bundle install To create and use gemsets the longer way: a. Create gemset # rvm gemset create my_proj b. Use the gemset # rvm gemset use my_proj c. Install a gem # gem install package_name d. Wipe all gems installed # rvm gemset empty my_proj e. Delete the gemset # rvm gemset delete my_proj f. Check your current gemset # rvm gemset name
2.19.2015
Open HTTP port 80 on CentOS
Got from here.
1. Look at the current iptables # iptables --line -vnL Chain INPUT (policy ACCEPT 0 packets, 0 bytes) num pkts bytes target prot opt in out source destination 1 0 0 ACCEPT udp -- virbr0 * 0.0.0.0/0 0.0.0.0/0 udp dpt:53 2 0 0 ACCEPT tcp -- virbr0 * 0.0.0.0/0 0.0.0.0/0 tcp dpt:53 3 0 0 ACCEPT udp -- virbr0 * 0.0.0.0/0 0.0.0.0/0 udp dpt:67 4 0 0 ACCEPT tcp -- virbr0 * 0.0.0.0/0 0.0.0.0/0 tcp dpt:67 5 195K 212M ACCEPT all -- * * 0.0.0.0/0 0.0.0.0/0 state RELATED,ESTABLISHED 6 3 252 ACCEPT icmp -- * * 0.0.0.0/0 0.0.0.0/0 7 74 5440 ACCEPT all -- lo * 0.0.0.0/0 0.0.0.0/0 8 16 864 ACCEPT tcp -- * * 0.0.0.0/0 0.0.0.0/0 state NEW tcp dpt:22 9 170K 39M REJECT all -- * * 0.0.0.0/0 0.0.0.0/0 reject-with icmp-host-prohibited 2. Inject rule, as long as it's before the REJECT line # iptables -I INPUT 5 -p tcp -m state --state NEW -m tcp --dport 80 -j ACCEPT 3. Save # service iptables save 4. Add httpd_t to the list of permissive domains (So we don't need to turn off selinux) # yum install policycoreutils-python # semanage permissive -a httpd_t
Subscribe to:
Posts (Atom)