Difference between revisions of "Linux utils"
From Wasya Wiki
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git branch | grep -e "^*" | cut -d' ' -f 2 | git branch | grep -e "^*" | cut -d' ' -f 2 | ||
| − | === increase number of open files, file descriptors == | + | === increase number of open files, file descriptors === |
From: /etc/security/limits.conf | From: /etc/security/limits.conf | ||
Revision as of 21:41, 30 August 2017
Contents
- 1 Utils
- 1.1 Find 10 largest files in a folder
- 1.2 ssh forwarding and such
- 1.3 Set date
- 1.4 Get date in milliseconds
- 1.5 check disks on ubuntu
- 1.6 Mount a block devise
- 1.7 check that a node is pingable in bash
- 1.8 how to tell if port 80 is listening?
- 1.9 how do I know if the system trusts the certificate?
- 1.10 how to tell if port 80 is listening? What is listening on a particular port?
- 1.11 ubuntu vpn
- 1.12 Find large files
- 1.13 see timestamps in history
- 1.14 Generate large random file
- 1.15 Add ssh key to a server
- 1.16 Add identity to a server
- 1.17 Create a user
- 1.18 Establish a simple ssh port forward
- 1.19 Reset Chef UI Password
- 1.20 mongo add member to cluster
- 1.21 install redis
- 1.22 Delete files older than 5 days
- 1.23 get children of a process
- 1.24 restrict resources given to a process
- 1.25 git check branch
- 1.26 increase number of open files, file descriptors
Utils
Find 10 largest files in a folder
du -a /var | sort -n -r | head -n 10
ssh forwarding and such
ssh -L 2222:machine2.example.org:22 machine1.example.org
with ssh-agent: ssh -tt ubuntu@piousbox.com ssh -tt ubuntu@10.0.1.157
Set date
sudo date --set "25 Sep 2013 15:00:00"
Get date in milliseconds
date -d 2017-05-05 +%s
check disks on ubuntu
sudo lsblk
Mount a block devise
From: https://www.digitalocean.com/community/tutorials/how-to-use-block-storage-on-digitalocean
parted /dev/sda mklabel gpt parted -a opt /dev/sda mkpart primary ext4 0% 100% mkfs.ext4 /dev/sda mkdir -p /data '/dev/sda /data ext4 defaults,nofail,discard 0 2' | sudo tee -a /etc/fstab mount -a
check that a node is pingable in bash
while ! ping -c1 bjjc_spec_22.ubuntu14 &>/dev/null; do :; done ;
how to tell if port 80 is listening?
telnet?
how do I know if the system trusts the certificate?
you use curl.
how to tell if port 80 is listening? What is listening on a particular port?
netstat -plnt
ubuntu vpn
https://hide.me/en/vpnsetup/ubuntu/openvpn/
Find large files
find / -xdev -type f -size +100M
see timestamps in history
echo 'export HISTTIMEFORMAT="%d/%m/%y %T "' >> ~/.bashrc ; source ~/.bashrc
Generate large random file
dd if=/dev/urandom of=/var/log/mongodb/randomFile bs=1M count=200
Add ssh key to a server
cat ~/.ssh/id_rsa.pub | ssh user@hostname 'cat >> .ssh/authorized_keys'
Add identity to a server
ssh-copy-id -i ~.ssh/key_name.pub user@host
Create a user
useradd? adduser?
su - <username> sudo visudo -f /etc/sudoers usernameusedforlogin ALL=(ALL) NOPASSWD:ALL sudo adduser --disabled-password <username> (and there is deluser) (I don't think I need this: usermod -aG sudo username ) - for making him a sudoer
Establish a simple ssh port forward
10.0.0.x is public, 10.0.1.x is private. Do:
sudo sysctl net.ipv4.ip_forward=1 sudo iptables -t nat -A PREROUTING -p tcp -d 10.0.0.229 --dport 2270 -j DNAT --to-destination 10.0.1.224:22 sudo iptables -t nat -A POSTROUTING -j MASQUERADE
Reset Chef UI Password
sudo -u opscode-pgsql /opt/chef-server/embedded/bin/psql opscode_chef update osc_users set hashed_password = '$2a$12$y31Wno2MKiGXS3FSgVg5UunKG48gJz0pRV//RMy1osDxVbrb0On4W' , salt ='$2a$12$y31Wno2MKiGXS3FSgVg5Uu' where username ='admin';
and login with user 'admin' and password 'password'.
mongo add member to cluster
operaeventrsX:PRIMARY> rs.add("10.138.96.89")
operaeventrsX:PRIMARY> rs.conf()
install redis
From: https://www.digitalocean.com/community/tutorials/how-to-configure-a-redis-cluster-on-ubuntu-14-04
sudo add-apt-repository ppa:chris-lea/redis-server sudo apt-get update sudo apt-get install redis-server redis-benchmark -q -n 1000 -c 10 -P 5
Delete files older than 5 days
find /path/to/files* -mtime +5 -exec rm {} \;
find /path/to/files* -type f -mtime +5 -exec rm {} -v \;
get children of a process
pgrep -P $your_process1_pid
restrict resources given to a process
sudo apt-get install cgroup-bin -y
sudo cgcreate -g memory:/rmGroup
sudo
echo $(( 500 * 1024 * 1024 )) > /sys/fs/cgroup/memory/rmGroup/memory.limit_in_bytes
# echo $(( 5000 * 1024 * 1024 )) > /sys/fs/cgroup/memory/rmGroup/memory.memsw.limit_in_bytes # swap only
# cgexec -g memory:rmGroup <command>
cgexec -g memory:rmGroup find cache/ -type f -mtime +10 -exec rm {} -v \;
git check branch
git branch | grep -e "^*" | cut -d' ' -f 2
increase number of open files, file descriptors
From: /etc/security/limits.conf
* - nofile 131072 * soft nofile 64000 * hard nofile 64000 root soft nofile 64000 root hard nofile 64000
