Useful Unix Commands

You may find these useful. Nothing is guaranteed. Some may be absent,
or function differently on some machines. Some of these commands can
do several different things, depending on the options you select. For
this sort of detail, you should use "man." For instance "man chmod"
will tell you all the things that chmod can do, and how to ask for them.


bc            desk calcualtor
cal           prints calendar of desired month
cat           catenate and print
cc            compile  C  code
cd            change directory  (Path;  empty;  branch;  or  ..)
chmod         change access rights of others
clear         clears the screen
cp            copy
date          gives today's date
dbx           debugger 
df            disk usage of the system at large
dirs          directory stack
du            tells your directory structure; with -a gives all files
echo          returns its input; useful with | and in shells
emacs         general purpose editor and program manager; can edit binary
ex            open file for editing (primitive)
ex -          ex with no output (suitable for shell scripts)
exit          leave an internal shell or script
f77           fortran compiler
fg            undoes control-Z ("foreground")
file          tells general type of a file (data, commands, troff, etc.)
find          locate a file  [Hard to use because of impenetrable syntax.]
finger        like who, including full names of users
from          who is my mail from?
grep          pattern search
head -N       cat first  N  lines  (default  N)
history       what were my recent commands to the system?
hostname      tells name of host you are on
jobs          processes that you can access
kill n        stops process  n;  get  n  from ps
last          who logged in and when; also `last [user]'
learn         tutorial lessons
lint          C  source inspection routine (I always found it useless)
login         allows you to log in again (new name, etc.)
ln            make a link (allows you to give more than one name to same file)
lpr -Pxxxx    use the xxxx printer
ls            list the current directory
mail          program for sending and receiving mail
man           look at manual entry
more          delivers output one screenful at a time
mv            rename
nice          limits your hogging of CPU time
od            octal dump
passwd        routine for changing your password
popd          delete one item from directory stack
printenv      states all the environment variables
ps            process status
ps -g         full process history
pushd         add entry to top of directory stack
quota -v      see how much disk is alloted to user
rehash        use after placing new executable files in bin/
renice        change `nice' level (not clear whether available to all)
rlogin        remote login (followed by name of machine)
rm            remove
rmdir         remove a directory [must be empty]
sort          alphabetize the file (various options for determining the order)
source        cause the shell to take input from a file, e.g. from .cshrc
spell         check spelling in a file
split         divide a file into smaller files
strings       find ASCII embedded in a binary file
style         checks a file for common foibles
tail -N       cat last  N  line  (default  N)
talk          direct connection with another user
tty           what terminal am I on?
u	      users currently on [long form: users]
unalias       disable some alias currently in force
vi            calls the visual editor
view          like  vi  but cannot write to the file
w             what people are doing
wc            word count for an ascii file
who           who's on the system
who am i      how am I logged in?
.cshrc        can hold aliases for commands
.exerc        can hold your preferred way of editing
.mailrc       can hold aliases for mailing
.plan         first line of this file is shown to any user who does finger
.project      first line of this file is shown to any user who does finger
!!            redo last command
!$            last argument in previous command
!:s/x/y	      redo previous command, substituting  y  in place of  x
!n            redo command  n
!n:p [etc.]   `print' command n.  (Show it, but don't execute it.)
!n:m	      mth argument to command n  [commandword has m = 0]
!n:s/x/y      redo command n, substituting  y  in place of  x
!xyz...       redo command beginning  xyz...
#	      first line of a cshell script; comment separator for same
%             shows current jobs (e.g. if you have something in background)
@             tells how all variables are set by the shell
&             put at end of command you want done in background
|             pipeline
*	      any sequence of letters
;             separates commands in a sequence
<   >         redirect
>>            append to end of indicated file
?	      any single character
^wrong^right  substitute `right' letters for `wrong' letters in a command
`...`         puts output of  ...  into the command line; e.g.  cat `ls`