Using DOS-like commands

There’s a package called mtools which is included with most of the distributions out there.

There are several commands for basic DOS stuff. For example, to directory the floppy drive, type mdir a:. This is rather handy–you don’t need to mount the floppy drive to use it.

Other commands are: mattrib , mcd, mcopy, mdel, mformat, mlabel, mren (rename), mmd, mrd, and mtype.

This doesn’t work for reading from hard disks. In that case, you would add entries to /etc/fstab, drive type msdos for fat16 partitions, and vfat for fat32.

More DOS-like commands

Many people are moving to Linux because they miss the stability of good old DOS. In that light, many users are typing DOS commands (which originated from UNIX in the first place) that look fine but cause errors. The command “cd..” in DOS is perfectly valid, but Linux balks. This is because “cd” is a command, and any parameter for that command must be separated from the command by a space. The same goes for “cd/” and “cd~”. A quick fix is here.

Use your favorite text editor in your home directory to edit the file “.bashrc”. The period is there on purpose, this hides the file from normal ls display.

Add the lines:

alias cd/=”cd /”
alias cd~=”cd ~”
alias cd..=”cd ..”

And I usually add these…

alias md=”mkdir”
alias rd=”rmdir -i”
alias rm=”rm -i”

and my first and still favorite alias…

alias ls=”ls –color”

alias is a powerful tool, and can be used in the .bashrc script as well as from the command line. You can, if you want to spend the time, create your own group of shell commands to suit how you work. As long as you put them in your .bashrc file, they’ll be there everytime you log in. Note that if you frequently log in as root, you might want to copy /home/username/.bashrc to /root/.bashrc to keep yourself sane.

Protecting yourself from being a spam base

Sendmail allows for someone to telnet to port 25 and do an expn (expand) to see what users and aliases are on your machine. Also, vrfy (verify) means someone can get legal e-mail addresses from your box and send spam through your machine.

Don’t want that, so look in your /etc/sendmail.cf file for a line that looks like this:

###############
# Options #
###############

Now cut and paste these next few lines below that:

# turning off the expand option and requiring a helo from
# a remote computer
Opnoexpn,novrfy,needmailhelo

Now there is no expansion, no verify, and sendmail requires a helo with a legitimate DNS in order to use the mailer.

Then look in your /etc/mail/aliases file and ensure you have only your own boxen and/or subnet in there as OK or RELAY. That will help cut down on spammers’ ability to find relay machines to do their dirty work for them.

A script for cleaning up after programs that create autosave and backup files.
Here is a simple two-liner which recursively descends a directory hierarchy removing emacs auto-save (#) and backup (~) files, .o files, and TeX .log files. It also compresses .tex files and README files. I call it ‘squeeze’ on my system.

#!/bin/sh
#SQUEEZE removes unnecessary files and compresses .tex and README files
#By Barry tolnas, tolnas@sun1.engr.utk.edu
#
echo squeezing $PWD
find $PWD \( -name \*~ -or -name \*.o -or -name \*.log -or -name \*\#\) -exec
rm -f {} \;
find $PWD \( -name \*.tex -or -name \*README\* -or -name \*readme\* \) -exec gzip -9 {} \;