Unix Commands

Change the property file value using SED

-i To update file (if not provided it will just print the output

-E Use extended regex syntax

s Replace syntax would be s/orignalstring/replacement_string/

server.id is the string which will be searched for. To handle blanks use :blank

\1 String followed by it will be replaced

last parameter will be file name to process

Before running the command

server = orignal_value

sed -i -E 's/^(server[[:blank:]]*=[[:blank:]]*).*/\18/' foo.txt

After

server=8

If you want to pass the replacement value dynamically instead use single quite and value inside double quote ie. '"$newvalue"'

Epoch Time conversion

echo `date +%s`

converts date to epoch format

To find the size of all files in the directory

du -sh *

Delete all blank lines in files and store in new file

sed '/^$/d' xyz.cfg > abc.cfg

To Map a remote port to local port with SSH

ssh -i ~/Projects/kay -L 8999:127.0.0.1:80 user@remoteip

For multiple ports, you can use -D <port> user@ip - then configure network in browser to use the tunnelling at the port specified in ssh.