Tuesday, July 14, 2015

My useful linux commands notes

show open files and programs holding it 
#lsof +L1

Repeatedly run a command and see output 

watch -n 1 date +%r

Create a password that works for Debian and Ubuntu  (can be used in Puppet manifests ) 

 mkpasswd -m sha-512

Create database (MySql) 

CREATE DATABASE databasename;

Create user for a database 

mysql> grant all privileges on databasename.* to 'user'@'host' \
identified by 'password';

if you want to access this database with that user over the network (tcp connection) replace the 'host' with the one you need or change to '%' to allow access from any host (a security threat) .

Delete database 

DROP DATABASE databasename;

Convert flac to mp3 - right in the flac files folder

(install flac and lame)
apt-get install flac lame

for f in *.flac; do flac -cd "$f" | lame -b 320 - "${f%.*}".mp3; done

Mount Windows shares 

mount -t cifs //FILE-SERVER-IP-ADDRESS/public /local/mountpoint -o user=nobody

Compress and Decompress Folder ( for backup or whatever ) - use p to preserve permissions

tar -zcvf outputfile.tar.gz /home/jerry/prog

tar -zxvf outputfile.tar.gz

Copy files over ssh using *.pem file authentication 

scp -i  mykey.pem somefile.txt root@ec2-123-123-123-123.compute-1.amazonaws.com:/tmp

Copy files to S3 bucket 

apt-get install s3cmd
( configure s3cmd to authenticate with your credentials, make sure you have the required permission for the bucket) 

s3cmd put file.tar.gz s3://bucketname/

VI(M) tips

make a .vimrc file in the user directory and in /etc/skel , type syntax on in it in order to always have syntax highlighting enabled.

Find each occurrence of 'foo' (in all lines), and replace it with 'bar'.
Find each occurrence of 'foo' (in the current line only), and replace it with 'bar'.
Change each 'foo' to 'bar', but ask for confirmation first.
Change only whole words exactly matching 'foo' to 'bar'; ask for confirmation.
Change each 'foo' (case insensitive) to 'bar'; ask for confirmation.
This may be wanted after using :set noignorecase to make searches case sensitive (the default).