Basic Unix Commands

c++ {filename}

A compiler for the C++ programming language. Command line parameters are similar to the ``cc'' compiler's. A typical invocation might be ``c++ -g file.cpp -o executablename -llib''. 

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cat {filename}

Prints out ( to the screen ) the contents of the named file. Can also be used to concatenate files. Say you want file1 and file2 to be all together in one file named file3. If file1 is first, then ``cat file1 file2 > file3'' will produce the correct file3. 

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cc

A compiler for the ``C'' programming language. ``cc'' is ANSI compatible on the SGI, IBM, and newer Sun machines. You might try also try ``gcc'', GNU CC, which is also available on the SGI, SUN, and IBM machines. A typical invocation might be ``cc -g file.c -o executablename -llib''. 

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cd {dirname}

Change current directory. Without a ``dirname'', it will return you to your home directory. Otherwise, it takes you to the directory named. ``cd /'' will take you to the root directory. 

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chmod {options}

Changes the permission modes of a file. If you type ``ls -l'' in a directory, you might get something like this:

    drwx------ 3 ertle 512 Jul 16 13:38 LaTeX/
    drwxr-xr-- 2 ertle 512 Jun22 12:26 X/
    drwxr-xr-x 3 ertle 512 Jul 13 16:29 Xroff/
    -rw-r--r-- 1 ertle 373 Oct 3 1992 o.me
    -rw-r--r-- 1 ertle 747 Nov 21 1992 profile
    -rwxr-xr-x 1 ertle 244 Jul 16 23:44 zap*

The first part of the line tells you the file's permissions. For example, the ``X'' file permissions start with a ``d'' which tells that it is a directory. The next three characters, ``rwx'' show that the owner has read, write, and execute permissions on this file. The next three characters, ``r-x'' shows that people in the same group have read and execute permission on the file. Finally, the last three characters ``r-'' show that everyone else only has read permission on that file ( To be able to enter a directory, you need read AND execute permission ). Users can use ``chmod'' to change these permissions. If the user didn't want anybody else to be able to enter the ``X'' directory, they would change the permissions to look like those of the LaTeX directory, like this : ``chmod og-rx X'' - this means remove the read (``r'' ) and execute (``x'') permissions from the group (``g'') and others (``o'').

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cmp {file1} {file2}

Compares the contents of two files from eachother. Reports the first different character found, and the line nummber. 

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cp {filename(s)}{path}

Copies files from one directory/filename to another. ``cp f1 f2'' makes a file ``f2'' identical to ``f1''. ``cp *.c src/'' copies all files that end in ``.c'' into the ``src'' subdirectory. 

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ctags

Creates a tags file for use with ex and vi. A tags file gives the location of functions and type definitions in a group of files. ex and vi use entries in the tags file to locate and display a definition. 

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date

Shows current date and time. 

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dbx {executable}

Source level debugger. In order to use this, you must use the ``-g'' option when compiling your source code. Allows you to set break-points, single step through the program, etc. 

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diff {file1} {file2}

Displays all the differences between two files or directories to the screen. 

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elm {login-name}

Runs a screen oriented mail reader. With a ``login-name'', starts elm to send mail to ``login-name''. Otherwise, it starts elm for an interactive session. 

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emacs {filename}

Runs the most recent version of the text editor named EMACS ( produced by the GNU project ). If filename is present, it will start editing that file. Type ``<CTRL>-x <CTRL>-h t'' to start a tutorial. ``<CTRL>-x <CTRL>-c'' will exit from emacs. 

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env

Prints out the values for all the current environment variables. Some typical environment variables are ``DISPLAY'', ``EDITOR'', and ``PRINTER''. 

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xemacs {filename}

An X version of emacs. 

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file filename(s)

Looks at ``filename(s)'' and tells what type of files they are. This is useful in checking a file to be sure that it is text before you ``cat'' it out ( using ``cat'' on binary files can be a bummer ). Example:

    ertle@newton (55)> file *
    useful.dvi: data
    useful.hlp: English text
    useful.tex: ascii text
    xwin.dvi: data
    xwin.tex: English text
    ertle@newton (56)>

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find

Searches the named directory and it's sub-directories for files. Most frequently called like this:

    find ./ -name ``t*'' -print

Which searches the current directory ( and all of its sub-directories ) for any files that begin with the letter 't' and then prints them out. If you are looking for a specific filename, then replace ``t*'' with ``filename'', and ``find'' will print out all incidences of this file.

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finger {login-name}

Without a ``login-name'', finger shows who is currently logged on the system, with limited information about them. With a ``login-name'' you get more detailed info, along with anything that is in that person's ``.plan'' file. 

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ftp {address}

File Transfer Program. ``ftp'' transfers files to and from a remote network site. There are many ftp-sites that will let you log in as ``anonymous'' and get software/data/documents from them for free. After connecting, ``ls'' will print out the files in the current directory, and ``get filename'' will transfer the named file into your local directory. Be sure to type ``binary'' before transferring non-ascii ( executable, compressed, archived, etc ) files. To exit ``ftp'' type ``bye''. See also ``xarchie''. 

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g++

GNU project's compiler for the C++ language. Parameters are similar to those of ``cc''. A typical invocation might be ``g++ -g filename.cpp -o executablename -llib''. More information available under ``libg++'' in the emacs information browser ( M-x info while in emacs ). 

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gcc

GNU project's compiler for the C language. Command line parameters are mostly similar to those of ``cc''. More information available under ``gcc'' in the emacs information browser ( M-x info while in emacs ). 

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gdb

GNU project's source level debugger. Must use the ``-g'' command line option when compiling to use this debugger. This debugger is superior to dbx when called from inside emacs ( M-x gdb ) because it gives you a full-screen look at the source code instead of line by line, and allows you to move around and make break-points in the source file. More information available under ``gdb'' in the emacs information browser ( M-x info while in emacs ). 

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ghostview {filename.ps}

X PostScript previewer. PostScript is a text processing and graphics language, and ghostview is handy for looking at the resulting page or picture before you send it to the printer. 

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gossip

Anonymous local message center. 

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ispell filename

Interactively checks the spelling of the named file, giving logical alternatives to the misspelled words. Type ``?'' to get help. ``ispell'' can be accessed from the command line, and also through emacs with M-x ispell-buffer. 

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jobs

Shows backgrounded (<CTRL>-z'ed) processes with pid #'s. If you use ``jobs'' to find the processes that you have suspended or are running in the background, what you get back might look like the following:

    [1] 21998 Suspended emacs useful.tex
    [2] - 22804 Suspended (signal) elm
    [3] + 22808 Suspended badb

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jove {filename}

Johnathan's Own Version of Emacs. Another emacs editor. Jove doesn't have as many features as GNU's emacs, but some people prefer it. <CTRL>-x <CTRL>-c to exit. 

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less filename

Displays file with minimal space.

kermit

File transfer program. Allows you to transfer files between computers - your PC at home to/from the computers at school, for instance. For more information, look in the online manual pages. 

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ln -s {source} {dest}

Creates a symbolic link from {source} to {dest}. {Source} can be a directory or a file.

Allows you to move around with ease instead of using long and complicated path names. 

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logout

Exits and disconnects your network connection. 

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lpq {-Pprintername}

Reports all print jobs in the queue for the named printer. If no printer is named with -Pprintername, but the ``PRINTER'' environment variable is set to a printer name, ``lpq'' will report on that printer. 

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lpr {-Pprintername}filename

Queues file ``filename'' to be printed on ``printer''. If no printer is specified with -Pprintername, but the ``PRINTER'' environment variable is set, then the job will be queued on that printer. 

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lprm {-Pprinter}{job-number}

Lprm removes a job or jobs from a printer's spooling queue ( i.e. it stops it from being printed or printing out the rest of the way ). Typically, you'd get the job number from the ``lpq'' command, and then use lprm to stop that job. 

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ls {directory}

Shows directory listing. If no ``directory'' is specified, ``ls'' prints the names of the files in the current directory.

ls -l {directory}

Shows long directory listing. If you type ``ls -l'' in a directory, you might get something like this:

    drwx------ 3 ertle 512 Jul 16 13:38 LaTeX/
    drwxr-xr-- 2 ertle 512 Jun 22 12:26 X/
    drwxr-xr-x 3 ertle 512 Jul 13 16:29 Xroff/
    -rw-r--r-- 1 ertle 373 Oct 3 1992 o.me
    -rw-r--r-- 1 ertle 747 Nov 21 1992 profile
    -rwxr-xr-x 1 ertle 244 Jul 16 23:44 zap*

The first part of the line tells you the file's permissions. For example, the ``X'' file permissions start with a ``d'' which tells that it is a directory. The next three characters, ``rwx'' show that the owner has read, write, and execute permissions on this file. The next three characters, ``r-x'' shows that people in the same group have read and execute permission on the file. Finally, the last three characters ``r-'' show that everyone else only has read permission on that file ( To be able to enter a directory, you need read AND execute permission )

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mail {login-name}

Read or send mail messages. If no ``login-name'' is specified, ``mail'' checks to see if you have any mail in your mail box. With a ``login-name'', ``mail'' will let you type in a message to send to that person. For more advanced mail processing, you might try ``elm'' or ``pine'' at the command line, or ``M-x mail'' in emacs. 

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mkdir dirname

Makes a sub-directory named ``dirname'' in the current directory. 

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man -k pattern

Shows all manual entries which have ``pattern'' in their description. 

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man {section}name

Shows the full manual page entry for ``name''. Without a section number, ``man'' may give you any or all man pages for that ``name''. For example, ``man write'' will give you the manual pages for the write command, and ``man 2 write'' will give you the system call for ``write'' ( usually from the C or Pascal programming language ). 

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more filename

Displays the contents of a file with pagebreaks. Usefull to use 'file' first so you don't display garbage.

mv filename path

Moves ``filename'' to ``path''. This might consist of a simple renaming of the file, ``mv file1 file2'', moving the file to a new directory, ``mv file1 /tmp/'', or both ``mv file1 /tmp/file2''. 

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pico

   Very basic text editor, same interface as pine

pine

Full featured graphical mail reader/sender. 'pine' will read your mail, 'pine username' will prepare a message to 'username'. 

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printers

Shows available printers and current status. 

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ps {options}

``ps'' reports that status of some or all of the processes currently running on the system. With no command line parameters, ``ps'' only shows processes that belong to you and that are attached to a controlling terminal. 

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pwd

Shows current working directory path. 

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quota -v

Shows current disk usage and limits. 

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rm filename(s)

Removes files. Careful with this one - it is irreversible. It is usually aliased ( in a user's .cshrc file ) to ``rm -i'' which insures that ``rm'' asks you if you are sure that you want to remove the named file. 

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rmdir dirname

Removes the directory ``dirname''. 

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rupall

Reports that status of local compute servers. 

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rwho

Similar to ``who'', but shows who is logged onto all emba machines as well as the local machine. Without ``-a'', rwho shows all the people with under one hour idle time. With the ``-a'', rwho shows everybody that is logged on. 

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setenv

Sets environment variables. Most frequently used to tell X which display you are on with ``setenv DISPLAY displayname:0''. Also used in .cshrc file to set ``EDITOR'' and ``PRINTER'' environment variables. This tells programs which editor you prefer, and which printer you want your output to be printed on. 

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spell {filename}

Checks the spelling of the words in the standard input by default, checks words in ``filename'' if a name is supplied on the command line. If a word is misspelled it is printed to stdout ( usually the screen ). 

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trn

Threaded, full page network news reader. Quicker than vn. 

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tin

Threaded, full page network news reader. Easier to use than trn. 

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vi {filename}

Runs the screen oriented text editor named ``vi''. If a filename is specified, you will be editing that file. Type ``[ESC]:q!'' to exit without making any changes. 

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vn

Runs the screen oriented network news program. Old and slow - maybe try ``trn'' or ``tin''. 

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whereis {command}

Reports the directory in which the {command} binary redides. 

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which {command}

Reports the directory from which the {command} would be run if it was given as a command line argument. 

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who

Shows who is currently logged on the system. The ``w'' command does the same thing, but gives slightly different info. 

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write loginname

Send a message to another user. Each line will be sent to the other person as you hit the carriage-return. Press <CTRL>-D to end the message. Write won't work if the other user has typed ``mesg n''. 

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xcalc

X scientific calculator. 

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xcalendar

X calendar. Interactive calendar program with a notebook capability. 

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xclock

X clock. 

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xforecast

X interface to national weather forecast. 

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xgdb

X interface to the gdb debugger. 

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xman

X interface to the online manual pages. 

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passwd

Interactively changes your password. 

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Click Here for more advanced UNIX commands.