Useful commands
new user to server
vi /etc/ssh/sshd_config
systemtcl restart sshd.service
scp - copying files among linux servers (r=recursive)
scp -r $USER@$SERVER:REMOTE_PATH LOCAL_PATH
count lines in files
wc -l FILENAME
sed - delete top lines of file (ie. log files) - 300000 is number of lines
sed -i '1,300000d' FILENAME
create group
groupadd GROUPNAME
check group exists
grep GROUPNAME /etc/group
add user to group (a=append, G=groupname that follows)
usermod -a -G GROUPNAME USERNAME
change group owner (R=recursive, FILE can also be a folder)
chgrp -R GROUPNAME FILE
allow group to write to folder
chmod -R g+w FOLDER