Q: How do I mask out files with a particular extension when using ls

You enable/disable extglob in the Bash shell. Type the blue content in the Terminal.

# enable extglob

$ shopt -s extglob

# show all files except those with .cmd extension. The '!' is a negation operator here.

$ ls !(*.cmd)

# disable extglob

$ shopt -u extglob

For more information on extglob, and additional operators, see man bash(1), and then search for extglob. Also, read this stackoverflow post on usage and other extglob operators.

A very common method used by many Unix users is

ls | grep -v '\.cmd$'

This can be expanded to

ls | grep -v '\.cmd$' | grep -v '\.fred$' | grep -v '\.another$' | etc...

or

ls | egrep -v '\.cmd$|\.fred$|\.george$|\.charlie$|\.paul$'

In bash as VikingOSX  points out ( note: added the d option to ls):

shopt -s extglob

ls -d !(*.cmd)

In ksh without having to turn on anything:

ls -d !(*.cmd)

In zsh there is different syntax:

ls -d *~*.cmd

In tcsh again different syntax:

ls -d ^*.cmd

Mark,

Thanks for adding the -d switch to avoid recursive descent into directories.