Generalities:

• Warning: The information below is more often than not incomplete. To see all the details, check the man pages.
• The syntax and arguments described below are specific for Linux. There might be small differences for Unix.
• To run a command in the background, put an & at its end (e.g.: emacs &).
  This will return the "shell-prompt", so that you can use the shell while the command you just issued is running (otherwise, you have to wait until the last command terminates before you can issue another command in the same shell).
• To STOP the job running in the foreground use CONTROL-Z; it can be resumed with fg. To KILL it, use CONTROL-C.
• Notational conventions:
  • an item enclosed between < and > has to be substituted by the appropriate value;
  • an item enclosed between [ and ] is optional.
  • the vertical bar | means "or".
• Commands:
  Some commands are discussed below in more detail, for the other check the man/info-page.

  help

  man, info (better organized man-pages; see more in the Emacs section, under the Info node)

  navigation and file handling

  ls, cd, mkdir, mv, rm, cp, tar, pwd, dirs, pushd, popd

  file viewing (without editing)

  more, less (the latter is more powerful)

  file editing

  emacs (my preference), vi

  printing

  lpq, lprm, lpr, kprinter

  e-mail

  thunderbird (by mozilla), alpine, mail

  (La)TeX related

  xdvi, dvips, dvipdf, pdflatex, vlatex

  images

  • to view: ghostview, gv, acroread, display, okular (supports many formats); xpdf, xv are no longer supported
  • to create: xfig
  • image processing:
    • convert file.jpg file.pdf (many more formats are handled)
    • collect PDF files into a single one:
      gs -dNOPAUSE -sDEVICE=pdfwrite -sOUTPUTFILE=new.pdf -dBATCH OLDFILES

  remote access

  ssh, scp, ftp, xon

  file permissions and ownership

  chmod, chown, chgrp

  job management

  jobs, bg, fg, ps (check processes), kill (kill a process or job)

  other shells

  csh, tcsh

  execute commands from a file

  source

  shell scripts

  other commands (see their man page)

  • rename: rename more files with one command
  • dos2unix, unix2dos: convert text files between unix/linux and windows (the newline character is different)
  • image conversions: e.g. convert file.jpg file.pdf
  • combine more PDF files into single one: gs -dNOPAUSE -sDEVICE=pdfwrite -sOUTPUTFILE=all.pdf -dBATCH FILES

Linux (or UNIX) Commands:

man

• purpose: on-line manual for Unix (or Linux)
• usage: man <program_name> or man -k <keyword>
• examples:
  • man man describes the use of the manual
  • man -k print lists commands that refer to printing

pwd

• purpose: print position in the file system (Print Working Directory); see also dirs
• usage: pwd

cd

• purpose: Change Directory
• usage: cd <directory_to_go>
• remarks:
  • If no target directory is specified, cd will change to the home directory, ~
  • A directory can be specified relative to the current location, or by a full pathname.
    A full pathname begings with a forward-slash, /, or a tilde, ~.
    A ~ by itself denotes the user's home directory.
    See the examples below.
• examples:
  • cd papers
    changes to the subdirectory papers of the current directory
  • cd ~/images
    changes to the directory ~/images, which is the directory images in the user's home directory; note that the full path is given!
  • cd /home/HOMER
    changes to the directory /home/HOMER, given by a full path
  • cd ~euclid
    changes to the home directory of the user whose login-name is euclid

dirs

• purpose: print position in the file system, use  ~  if we are inside the home directory; see also pwd
• Note: actually, dirs prints the whole directory stack; the current directory is the first in the list. To learn more about this stack, look at pushd and popd.
• usage: dirs

ls

• purpose: list content of a directory, or information about files (LiSt)
• usage: ls [-ladR] [<file_names> <directory_names>]
  • if no file or directory is specified, it lists the content of the current directory
  • -a shows all files (including those that start with a dot)
  • -l shows the long form, describing permissions, size etc.
  • -d lists directory entries instead of their content
  • -R descends recursively through the directories
• examples:
  • ls -al ~    gives long information for the whole content of your home directory
  • ls -ld ~    gives long information only about your home directory, not its content

mkdir

• purpose: create a new directory (MaKe DIRectory)
• usage: mkdir <directory_name>

chmod

• purpose: change read/write/execute permissions (CHange MODe)
• usage: chmod [-R] <whoHOWwhat> <target>
  • who is any combination of
    • u for user
    • g for group
    • o for other
    • a for all (i.e., user, group and others)
  • HOW can be one of
    • = for set
    • + for add
    • - for remove
  • what is any combination of
    • r for read
    • w for write
    • x for execute
  • target is a list of files and directories
  • -R causes chmod to descend recursively through the directories
• examples:
  • chmod -R go-rw my_papers protects the directory my_papers, and any file or directory beneath it, from being read/written by group and others
  • chmod a+r index.html adds for everyone the permission to read the file index.html

fg

• purpose: brings jobs that are suspended or in the background to the foreground (ForeGround)
• Note: an alternative to fg is to issue the command %job_number, or %first_few_letters. E.g.: %2 will bring to the foreground the job having number 2, %em will do the same for emacs (assuming there is a unique match)
• usage: fg [job_specification]
  • job_specification can be %job_number or %first_few_letters (as above)
  • if job_specification is missing, fg will resume the current job
  • otherwise, it will resume the specified job
  • to find the job numbers, use the command jobs.
• examples: fg %1, fg %em

bg

• purpose: takes jobs that are suspended to the background (BackGround)
• usage: similar to fg

jobs

• purpose: lists the jobs currently executing (running, suspended etc.) in the shell where the command is issued
• usage: jobs
  • the current job is always flagged with a +, and the previous job with a -

ssh

• purpose: connect securely to another machine (Secure SHell)
• usage: ssh [-l login_name] [hostname | user@hostname] [command]
• examples:
  • ssh math.uh.edu attempts to connect to math.uh.edu, using as login_name that of the user issuing the command
  • ssh -l john math or ssh john@math attemps to connect to math as user john
• NOTE: if, e.g., math is not recognized as hostname, you might have to give its full name, math.uh.edu. This is expanded by, roughly speaking, the DNS (Domain Name Server) to the "real" address, which is a number, something like 132.8.182.9.

scp

• purpose: copy securely from another machine (Secure CoPy)
• WARNING: scp will overwrite files without asking for confirmation!
• usage: scp [[user@]host1:]file1 [...] [[user@]host2:]file2
• example: scp john@math.berkeley.edu:papers/text text_berkeley
  copies the file ~/papers/text from the john@math.berkeley.edu account to the file text_berkeley on the machine (and account) from where scp was issued

alpine (based on pine)

• purpose: lets you read, send and handle emails (pine stands for Program for Internet News and Email)
• usage:
  • alpine, and follow the instructions/choices on the screen
  • you may have to set in ~/.pinerc the variable "rsh-open-timeout" to zero.

xon

• purpose: start an X program on a remote machine
• usage: xon remote-host [-user user-name] [command]
• remarks: when no command is specified, xon runs xterm.
• example: xon math netscape starts netscape on math

tar

• purpose: gather more files/directories into a single file; the same command (with different parameters) will reconstruct the files/directories.
  This is useful, say, to make a copy of a directory (e.g., over the Internet), or to compress it (first tar the directory, then compress the resulting file - using gzip & gunzip or bzip2 & bunzip2, etc.)
• usage:
  • to create a tar file: tar cvpf <TARGET_FILE.tar> <INPUT>
  • to extract the files: tar xvpf <TARED_STUFF>
  The INPUT can be a list of files and/or directories.
• example:
  • tar cvpf school.tar ~/2001/school will tar the directory (or file) ~/2001/school into the file school.tar
  • tar xvpf school.tar will reconstruct the directory (or file) school in the current directory;
    NOTE: the file school.tar is not removed
• remarks: see the explanation of the parameters in the man-page;
  there are many more possibilities!

lpq

• purpose: check the laser printer queue (Laser Printer Queue)
• usage:
  • lpq  
    The status of the default printer is checked (if such a printer is defined).
  • lpr -P <printer_name>  
    The status of the specified printer is checked.
• examples: lpq -P rm645
  check the status of the printer rm645 (which is the default printer)

kprinter

• purpose: open a dialog box in which you can select various parameters, including:
  • the printer
  • the file to print (see the "folder" icon near the right edge)
  • the number of pages per sheet (see "properties" near the printer name)
  • and much more; see for example the section More KDEPrint "Goodies" in Chapter 3 of kprinter's Help
• usage:
  • kprinter <file>  
  • kprinter

lpr

• purpose: print a PostScript or text (ASCII) file to the printer (Laser PRinter)
  • WARNING: DO NOT SEND OTHER FILES TO THE PRINTER. The result will be a lot of garbage pages.
  • If this however happened, you can try to stop the printing with the command lprm - (this might not help always).
  • You can check the status of a printer (e.g., jobs in the queue) with the command lpq.
• usage:
  • lpr <file>  
    The file will be sent to the default printer.
    If there is no default printer defined, an error message will be issued, and nothing printed.
  • lpr -P <printer_name> <file>  
    The file is sent to the printer specified.
• examples: lpr -P rm645 exam.ps
  (rm645 is the default printer)

lprm

• purpose: remove jobs from the printer (Laser Printer ReMove)
  Normally, one can remove only his/her own jobs.
• usage:
  • You might have to issue the command from the same machine from where the job was sent to the printer.
  • If the action is directed to the default printer, the -P parameter can be omitted.
  • If the flag - is specified, all queues will be searched (in some versions the corresponding flag is -a, check the man-page).
  • lprm -P <printer_name>
    remove the last job that you submitted to the specified printer
  • lprm -
    remove the last job that you submitted from all printer queues
  • lprm -P <printer_name> <number>
    remove job number <number> from the queue (the job numbers can be seen with lpq)
  • lprm -P <printer_name> all
    remove all your jobs from the queue
• examples:
  • lprm - all
    remove all your jobs in all queues
  • lprm -P rm645 1 4
    remove jobs 1 and 4 from the printer rm645