command switches/ flags

* Switches control behavior of commands and services.
* Switches can require arquments
* Switches can be combined for cumulative impact
* e.g.:-
# ls -a

complete list, including hidden files

# ls -l
detailed list of file, including ownerships, permissions, size, etc.

# ls -al
combined complete + detailed list of files.

# ps -a
complete process list for all users

# ps -x
include processes with no controlling terminals

# ps -w
increase max column width to 132

# ps -axw
combined process list of above flags.

# kill -HUP pid
send a HUP signal to service/ process

# chown -R username directory
recursively change ownership

# chmod -R g+w directory
recursively allow group to write to directory

# grep -i 'local' /etc/hosts
case insensitive search

# tail -F /var/log/messages
show changes at end of file in real time

* Full manual for each command can be invoked by 'man' command, e.g.
man ls