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The University of Texas at Austin

FAQ

Unix
  1. What happened to FTP access?
  2. How do I change the colors for the syntax highlighting in xemacs? The defaults are ugly.
  3. Where is National Instruments' Labview program located?
  4. How do I edit the "Plan" that people see when they finger me? I have a .plan file; why can't people see it?
  5. How do I find a process I know I must have running that I can't see? How do I get rid of a process I don't want?
  6. How do I remove or access a file with the name '-something' or containing another strange character?
  7. How can I use the CD-ROM drives on the departmental Linux or Solaris machines?
  8. Can I mount my own external storage (mp3 player, hard drive, thumb drive, etc) on the unix machines?
  9. How do I change my display? What does that mean? How do I run a program on one machine and have it display on the screen of another machine?
  10. What is "public" software? I'm having trouble with a program installed in /p/bin (type which [programname] to find out where something is installed.) How do I install software in "public"?
  11. Why does "find /" take so long? How do I find a file in the filesystem, knowing its name? How do I use locate? How do I use find?
  12. I just accidentally deleted something I need (or just realized I need something I deleted a while ago). What can I do now?
  13. How do I use the the floppy drives on the Solaris machines? On the Linux machines?
  14. How can I check how much disk space I'm using? Is there a command to check how much disk space is being used by a user?
  15. How can I find out the names of some computers I can use? What machines are publically available on the CS network? What's a "public" machine?
  16. How can I add a directory to my font path? If I know where a font is and I want to use it, how can I make programs recognize it?
  17. How can I use a different size font for the windows I have open? For other applications?
  18. How can I create a mailing list?
  19. What is Perl? Is Perl available on the CS systems?
  20. How can I create a new group?
  21. I can't cd into (or list files in) the directory /stage/net/www/[something] (or /stage/[something], or /tmp_mnt/[something]) -- it says "No such file or directory." What's wrong?
  22. I have a directory with a permission "s" (or "S"). What does that mean?
  23. I like being able to use emacs or vi style keybindings in applications other than those editors. How can I do this?
What happened to FTP access?

In our continuing effort to keep UTCS a secure network, FTP access will no longer be allowed from outside of our network. The FTP protocol transmits your password in cleartext which presents a security concern.

If you need remote file access, we recommend using an SFTP or SCP client, both of which use strong encryption to protect your password.

For Windows, we recommend:

For Mac OS X, we recommend:

How do I change the colors for the syntax highlighting in xemacs? The defaults are ugly.

Just click on the keyword that has the color you want to change and go to options->customize->face and then type in font-lock-keyword-face.

Where is National Instruments' Labview program located?

It is available as /lusr/labview/lv50/labview

How do I edit the "Plan" that people see when they finger me? I have a .plan file; why can't people see it?

The "Plan" is a printout of a file named .plan in your home directory. For people to see it, the file has to be world-readable and your home directory will have to be world-executable.

How do I find a process I know I must have running that I can't see? How do I get rid of a process I don't want?

To find a runaway process, use the ps command. The flag to show all your processes (not just active ones) can differ from platform to platform; on the suns or linux machines type ps -gxu. On any platform, the man pages (man ps) show all possible flags.

To kill a process once you've found its process ID (PID), type "kill PID". If that doesn't work, you can use "kill -9 PID".You should never issue the kill -9 -1 command unless you are outside of the X window system. Doing so with X running will freeze the console and require a reboot by the staff.

How do I remove or access a file with the name '-something' or containing another strange character ?

If your file starts with a minus, use the -- flag to rm; if your file is named -g, then your rm command would look like rm -- -g. As well, and especially if you have an unprintable character (output from ls looks like ?ile) you might try something like rm -i ./*ile which will also work for commands other than rm (grep for instance).

How can I use the CD-ROM drives on the departmental Linux or Solaris machines?

Under Solaris, any data CD which is inserted is automatically mounted under the /cdrom directory. To get your CD out of the drive, use the eject command. Under Linux, you have to mount data CDs yourself using the command mount /cdrom. You must run the command umount /cdrom before you will be able to eject the disk.

You can use xmcd (among others) to play audio CDs on the Solaris machines. To play audio CDs, you have to put the CD in the drive before you start xmcd.xmcd is no longer supported on the Linux machines, so try either gnome-cd (gnome), kscd (kde), or another option for playing music CD's on linux machines is xmms. It is somewhat complex to setup, but uses digital audio extraction instead of analog playback to get the music, meaning you can access the music as a file rather than only via your headphones. Here are the steps for using xmms to play a CD:

  1. run xmms from the command line
  2. put focus into the main (cd-player-controls-looking) window, and hit control-p
  3. choose the "Audio I/O Plugins" tab
  4. highlight "CD Audio Player" in the list of input plugin selections
  5. make sure the "enable plugin" button is depressed
  6. hit configure (the configure button nearest to the input plugins list); this should bring up another dialog box
  7. for device, use /dev/cdrom
  8. for directory, pick something (say, make a directory in /var/local or /tmp that you won't otherwise use)
  9. selection digital audio extraction as play mode
  10. then try "check drive"
  11. assuming all that worked, hit the "add drive" button and exit xmms
  12. then reopen xmms, focus its main window, hit l and navigate to that directory you created/specified above
  13. you should be able to play whatever is "in" it (fake files representing tracks).
troubleshooting:
Can I mount my own external storage (mp3 player, hard drive, thumb drive, etc) on the unix machines?

Most of our Linux machines support USB2 (high speed) and all support USB1. I f your device is (or can pretend to be) a standard USB mass-storage device with a supported (ext2, ext3, DOS/Win, ISO9660) filesystem on it, and comes in some sort of standard partition or whole-device-is-a-filesystem format, then you shoul d be able to mount it with the /lusr/bin/usbmount command. You *must* then unmount it after usage to prevent data loss! If that command fails, please send to gripe@cs the output of running the command with your drive plugged in and we will try to help you get it working. We have no support for firewire on a ny of our machines at this time, and some USB devices which require special driv ers will not work. However, the majority of off-the-shelf devices we've tested work fine, including the dumber variety of USB flash-memory-card readers.

How do I change my display? What does that mean? How do I run a program on one machine and have it display on the screen of another machine?

X applications figure out where to display windows by looking at the $DISPLAY environment variable. In the simplest case, if you want to run something on one machine, but have it display to another you would change that variable on the machine you're running the program on, usually to the name of the machine you're logged into followed by ':0.0'.

If you want to display an Xwindows program run on 'mjollnir' and have it display on 'ahab', under csh or tcsh you would type: ahab% rlogin mjollnir mjollnir% setenv DISPLAY ahab:0.0 mjollnir% <your command> & and under bash or sh, you would replace the middle line above with DISPLAY=ahab:0.0 ; export $DISPLAY

However unless you are familiar with, and adjust your X window security setting with xauth or xhost (NEVER use xhost +  ! Anyone on the internet can look at your screen and see what you type!), a better alternative is simply to connect with ssh. ssh is like rsh, except that it automatically sets your $DISPLAY and manages the security of your display in a very safe fashion.

What is "public" software? I'm having trouble with a program installed in /p/bin (type which [programname] to find out where something is installed.) How do I install software in "public"?

The "public" software is anything installed in the /p or /public directory (typically, actual programs are in /p/bin). This software is installed by non-staff (students, researchers, or professors) and is not monitored, installed or maintained by the staff; if you're having trouble with a particular program, contact the person who installed that package (as shown by ls -l) directly, or email public@cs.utexas.edu, which is a mailing list of all people who maintain programs in /public. If you want to enable your account to install software in /public, email udb@cs.utexas.ed and they'll add you to the group and mailing list.

Why does "find /" take so long? How do I find a file in the filesystem, knowing its name? How do I use locate? How do I use find?

Please don't use "find /", as it's very slow and a real drain on the network. Use locate by typing locate [string], where [string] is the name of the file you want to find, or part of the name. It's more appropriate to use find to find something in a fairly small area, such as your home directory or a /projects directory, neither of which are searched by locate. The basic find syntax is 'find [path to search] [expression to search for]'; please read the man page for find, for more detailed information.

I just accidentally deleted something I need (or just realized I need something I deleted a while ago). What can I do now?

First, you should try recovering the file from snapshots yourself; to learn how view the documentation on recovering files from snapshots. If that fails, email operator@cs.utexas.edu and ask them to restore your files. Include the following information:

How do I use the the floppy drives on the Solaris machines? On the Linux machines?

Accessing a floppy is different on the linux and solaris machines.

On solaris, you can only access a PC-formatted (dos/windows) floppy. You should use the commands mdir, mcopy and eject. You can use the manual pages to look up these commands by typing 'man [command]', but the basic idea is:

On linux, you can read a floppy with many different types of filesystem (dos/win, linux, cdrom, but not mac or BSD/solaris) as follows: put your floppy in, and type mount /floppy Then you can cd /floppy to get to your files, and use the standard unix tools to access, modify, and delete them. Don't forget to run umount /floppy (after making sure you have no processes or windows open that are using /floppy as the current directory) before you remove it, or your data may not be saved!

How can I check how much disk space I'm using? Is there a command to check how much disk space is being used by a user?

You can find out how much disk space is in a particular directory (such as someone's home directory) with the command du -sk, if you have permissions on that directory -- if it's yours or if it's world-readable. You can also check the directory /lusr/share/doc/disk-usage for reports on who's using how much space on specific disks, although that information is updated hourly, not in real-time.

How can I find out the names of some computers I can use? What machines are publically available on the CS network? What's a "public" machine?

A "public" machine is a machine that can be logged into by anyone with a CS account. You can use the command cshosts to find out more information about machines on the CS network; type cshosts help or man cshosts for more information about how to use it. Alternatively, you can visit public UNIX host status page for a list of public hosts and their current statuses.

How can I add a directory to my font path? If I know where a font is and I want to use it, how can I make programs recognize it?

Use the following command to add a directory to your font path. xset fp+ [name of directory] You may need to run xset fp rehashafterwards to add its fonts to the available listing.

How can I use a different size font for the windows I have open? For other applications?

The default font for terminal windows run via the 'xterm' and 'rxvt' programs is set in your ~/.Xdefaults file; the line looks like XTerm*font: 9x15 . Change the 9x15 to the font you want to use. You can change the font for any application in the same way. To pick a font, use the "xfontsel" application. (10x20 is slightly larger than 9x15, and 8x13 is slightly smaller.)

You can also set the font upon startup to most Xwindows applications and terminals (including xterm, rxvt, konsole, gnome-terminal, etc) via arguments to the command, like so: rxvt -fn '-sony-*-*-*-*-*-*-*-*-*-*-*-*-*' Don't forget to put the argument in single quotes (') if it contains shell metacharacters such as asterisks.

How can I create a mailing list?

Mailing lists, for the most part, are only created for "official" department purposes (lists of students in a class created for TAs, etc). These are the steps to take to create one:

The alias, if approved, will become effective within one or two business days.

What is Perl? Is Perl available on the CS systems?

Yes, the directory location is: /lusr/bin/perl. Perl (Practical Extraction and Report Language) is a scripting language often used under UNIX. Perl provides access to all operating system calls but is interpreted (not compiled), so it is faster to code and easier to debug than writing, say, C; but it typically runs more slowly.

How can I create a new group?

New UNIX groups, for the most part, are only created for "official" department purposes (students working together in a class created at the request of the professor, for example). If you have a reason to need a group, Email udb@cs.utexas.edu, giving the name of the group you want, the login names of the people who need to be in it, and the purpose of the group. The group, if approved, will be created within one or two business days.

I can't cd into (or list files in) the directory /stage/net/www/[something] (or /stage/[something], or /tmp_mnt/[something]) -- it says "No such file or directory." What's wrong?

Neither /tmp_mnt nor /stage is a literal pathname; /tmp_mnt is a mount point provided by the automount system and cd'ing into it may not work or list all of the directories. You should never use either of these in specifying a unix pathname. In CS, the path to a user's home directory is /u/[login-name] and to a web directory is /u/[login-name]/public_html.

I have a directory with a permission "s" (or "S"). What does that mean?

It means that all new files will be created with the same group id as that of the parent directory. The lowercase s shows that the directory is also executable, meaning you can cd into it.

I like being able to use emacs or vi style key bindings (keyboard shortcuts) to navigate while typing in applications other than those editors. How can I do this?

That functionality is typically provided by the GNU Readline Library, which is used by many applications such as shells (bash, tcsh, zsh), mailreaders (mutt) and many others. However, some applications are not readline-aware but fear not, there is a way to make them behave like they are! We have installed the program rlwrap which provides readline functionality to any text input program. It is in the standard path and can be run with any client application, though there are many applications (anything graphical for instance) with which it would not make sense. An example execution would be:rlwrap acl which starts the allegro common lisp interpreter with readline functionality.There is a man page (rlwrap(1)) for your edification.