file you would put ls = "ls -F"

there is a file you put the line

ls "ls -F"

so that when you type ls, it will automatically do ls -F

i forget what the filename was. does anyone know it?

I think you're probably thinking of .bashrc if you're using the BASH shell, that is. If you're using a different shell then the filename would be different.

.bashrc is the file used by the bash shell to store any user aliases and some user preferences that I can't think of currently. Normally if you wanted the ls -F command to be executed everytime you typed "ls" you would write

alias ls='ls -F' either at the command line itself or as a line in .bashrc in your home directory.

To see a list of all of your current alias's just type "alias" at the command line.

thank a lot. it worked.

stop this stupidities, let ls be ls
i mean, don't change native cmds, if you need your
own ls, write alias mls='ls -what-you-want'
an example:
cd /usr/xxx; tar cf - . |(cd /tmp; tar xfp -)
you will spend days to figure out, why it core dump !!
solution: cd is an alias
cd or ls does not matter, a lot of sys-shells use them
what when (after login) you starts /etc/qqq/abc that
use 'ls' AND expects a precise output ?