GNU/Unix and XWindows Commands

1. Linux Distributions
2. FS Mgt (a. Navig'n, b. File Display, c. File Search and Location, d. File Permissions, e. FS Hierarchy Standard) {LPI-101}
3. Text Processing (Text Editors, Text Utilities, Printing, Latex & Tex/Type-Setting) {LPI-101; LPI-102}
4. Documentation {LPI-101}
5. System Management (Process Management + System Status Cmds, Time and Host Status)
6. Internet (Communication Tools)
7. XWindows (XWindows, File System, Personal Mgmt)
8. Multimedia (Graphics, Audio, Video, Games)
9. Desktops (Gnome, KDE) {SkillDrill:"Gnome Implementn"}

0. Linux Distributions

• WinLinux http://www.winlinux.net/
• Lindows
• Xandros
• Win4Lin: run windows program inside linux
• Cygwin: Linux-like environment for Windows http://www.cygwin.com
• Monkey Linux: Install Linux as a File in Windows http://www.spsselib.hiedu.cz/monkey; http://projectdevolve.tripod.com/
• WinAxe: Networking Win-Linux http://labf.com/winaxe/index.html
• Knoppix: run Linux on a CD

I. File System Management

Conventions: squares = files or env. vars; disc = example commands/cmd line options; circle = subcmds.

a. Navigation: Working with Files, Directories and Links

ext2 Filenames can be up to 256 characters in length, may include small and capital letters, numbers and other characters, such as -, ., _. Files can be delimited by any printable character. A dot `.' indicates a relative path (eg ./ or ../) not an absolute one.

Login
• passwd = Gnome Icon > Programs > System > Change Password
  • 6 < passwd < 255 chars + contain at least 1 alphanumeric char + no dict word + no login id + not like current passwd
• User Info who, w, users
  • $whoami -> samar
  • $who am i -> alpha.iopb.in!abbas pts/2 Jul 29 21:15
  • $groups -> floppy xgroup
  • $rusers (remote users)
  • $id -> uid=254(abbas) gid=201(xgrp) groups=201(xgrp)
• Virtual Consoles = default 6 virtual consoles: Ctrl-Alt-F[1-6]; Ctrl-Alt-F7 = X if running Directories
• cd (`change dir')
  • $cd = $cd ~ = $cd ~abbas     (return to home dir $HOME)
  • $cd -   (goto previous dir $OLDPWD) [rh033,3-4]
• mkdir (`make directory')
  • -m ijk (`mode') | -p (make `parent' dir's)
  • $mkdir -m 700 d     (close new directory for all other users)
  • $mkdir -p {d1,d2}/{sd1,sd2}/{ssd3,}   (create parent dirs d1/sd1/ssd3, etc.)
• rmdir (`remove directory' if empty; rm -r|rf to remove non-empty dirs)
  • -p (`parent': remove empty parent dir's)
  • $rmdir d     (remove directory d)
• df (report `disk filesystem usage' in units of 1024 bytes + info re. disk partitions and mount points]
  • -a (all) | -i (`inode' usage) | -k (`kB') | -m (`MB') | -h (`human-readable') | -t nfs|hsfs|cdfs|pcfs (`type': nfs, High Sierra cdrom, HP-UX cdrom or MSDOS fs) | -T (`type' of each fs shown) | -x nfs (`eXclude' fstype)
  • $df -m -t nfs     (show usage in MB of mounted NFS filesystems)
  • $df -h   (o/p in k, M, G)
• du (report `disk usage' of current/specified directory in units of 1024 bytes)
  • -a (`all' files' info, not just dir's) | -b (`bytes' not default kB) | -k (`kilobytes'; default) | -h (`human-readable' size letters) | -H (`Human-readable'; but powers of 1000 not 1024) | -m (`MB') | -s (`summarize') | -D (`dereference' symbolic link + show their dir. usage)
  • HP-UX reports sizes twice the correct BSD NFS sizes
  • $du -D /usr/slnk     (`show directory usage of symbolic link')
  • $du -ak     (show directory and all file sizes in kB)
  • $du -sh     (space, human readable)
• tree (`show directory tree')
  • -a (`all' files, incl. hidden files) | -d (`dir's' only) | -f (`full path prefix') | -n (`no color') | -p (show `permissions') | -s (`size') | -u (print `username' else uid) | -g (`group name' else gid) | -q (`question mark' for non-printable char's in filenames not default carets) | -t (sort by `time modified' instead of alphabetically) | -C (`color on') | -D (`date' of last modification time) | -F (indicate `file type': / dir, * exec., = socket files) | -N (show `non-printable' char's in filenames as is) | -P *.txt (list only files matching `pattern')
  • $tree     (show directory tree)
  • $tree -s     (show sizes of tree files)
  • $tree -ns | less     (pagewise display of hierarchy with sizes and without color)
• pwd (`print working directory') [kamran.139] Files
• cp (`copy')
  • -f (`force' overwrite) | -i (`interactive': prompt before overwrite) | -l (make hard `links' instead of copies of files) | -p (`preserve' owner, perm's and timestamps) | -r (`recursively' cp whole dir trees) | -R (`recursively' cp whole dir trees) | -s (make `symbolic links' instead of copies of files) | -u (`update': overwrite old files only) | -v (`verbose': print name of each file before cp'g it)
  • $cp ../dir/f.txt .     (copy file f.txt in a directory dir under the superdirectory to the present dir)
  • $cp -a d1 d2     (cp entire dir tree, preserving modif times; $cp -R d1 d2 cp's dir tree but changes modif times)
• mv (`move' - actually renamg file)
  • -f (`force' overwrite) | -i (`interactive')
  • $mv f1.txt f2.txt; $mv dir1 dir2; $ls -i     (move file/dir, verify inode is same)
  • $mv f1.txt ~surya/dir/subdir     (move file to a subdir in /home/surya)
• rm (`remove')
  • -f (`force' overwrite) | -i (`interactive') | -r / -R (`recursive')
  • $rm -- -f   or   $rm ./-f     (remove file called -f)
  • $rm *.d??     (erase all files having a three-lettered suffix followed by two char's)
  • $rm -r cache/     (recursively remove all files and subdir's of a dir called cache, cf. -rf option)
• touch ( update file time stamp, or create a new empty file)
  • -a (change `access' time only) | -c (`creation-no': do not create non-existent files) | -d mmddhhmm (use given `date') | -t mmddhhmm (use given `time' instead of current time)
  • $touch {hello,bye}.{txt,tex,blk} (create multiple files)
  Links
• stat (show meta-data in inode; $stat /etc/passwd; $ls -i show inode no)
• ln (create links between files)
  • -s (make `symbolic/soft link' not hard one)
  • $ln f hl.lk; ls -i; ls -l; rm f     (create hard link; hard link still exists!)
  • $ln -s f sl.lk; ls -i; ls -l; rm sl.lk     (create symbolic/soft link instead of hard link; test with $ls -i and $pico new.lnk ; link only erased not old.txt)

  Definition of Hard Link : - Another name for an existing file. link and the original share the same inode (indexed node no.) containing all meta-data (data about data) about the file. hard links to directories are not possible hard links cannot cross FS boundaries/partitions [ file's inode = HD's MBR = partition's superblock ] (all are areas set aside to contain meta-data about the device) file present in FS as long as 1 hd ln remains Hard Link: /\/\ Soft Link: /\ / /\ \ / /\ /\ / /in\ \ / /in\ /in\ \ \od/ / \ \o1/ \o2/ \ \/ / \ \/ \/ \/\/ \/ Definition of Symbolic/Soft Link : - A special linux file type actually referring ie. pointing to a different file. [info ln] soft link is a file type; soft links can span FS/HD boundaries (unlike HL) soft links to dirs possible (unlike HL) some properties not fooled by soft links file being linked neednot exist perm(SL) = 777 always & default size of SL = no. chars of target filename not supported by older system kernels (eg. Sys.V.3)

b. File Display Listing, Viewing and Displaying Files.

• ls (`list' contents of dir)
  • -a (show `all' files, incl. hidden dot files) | -l (`long' listing) | -R (`recursive' listing of subdir's) | -t (sort by modif'n `time') | -r (`reverse' sort) | -i (`inode' no)
  • $ls -la     (long listing of all files, eg.:)

  drwxr-xr-x  18 abbas  user_loc  1024 Sep 19 17:03 Dinosaur
  -rw-------   1 abbas  user_loc 11565 Mar 25  2001 permian.txt
  

  This output consists of [welsh.85]:

  • File type field
  • Permission Fields
  • Number of Hard Links
  • Owner
  • Group
  • Size in Bytes (for dir's, the bytes used to store dir info)
  • Date and Time of Last Modification
  • Name of the file/dir

  File-type subfield : The first subfield [welsh.202] -

  • - : ordinary file
  • d : dir
  • l : symbolic link
  • b : block dev special file
  • c : character dev special file
  • $ls -lR | less     (long listing of subdir's piped to less)
  • $ls --color /dev     (list c|b files in color)
    
  • last modifd time: $ls -l; last-access t $ls -lu; inode change t $ls -lc; creatn time not stored
  • /etc/DIR_COLORS or ~/.dir_colors - provide the colors for $ls [welsh.84] [info tree has ~/.dircolors]
  • $LS_COLORS - $LS_COLORS=*.tex=1:*.html=34:*.txt=35; export LS_COLORS which can also be set via $dircolors)
• cat (`concatenate' files and prt to o/p; simplest txt editor)
  • -n (`number' all output lines) | -a (`all' incl. ctrl chars) | -s (`squeeze multi blank lines' to one only)
  • $cat f.txt     (display file)
  • $cat f1.txt f2.txt > f3.txt     (concatenate two files, redirecting output to a new file)
  • Editing : By redirecting the output from cat to a file, files can be created, whence Ctrl-D terminates the process, eg.

         $cat > f.txt
         Hello Everybody!
         Samar Abbas was here
         ^D 

  • $cat >> f.txt would instead append the text to existing file.
    
  • ^D twice if in middle of a line, once if on blank line.
• tac (`reverse concatenate')
  • -r (treat separator as `regex')
• head (output the first part of file, first 10 lines by default)
  • -c n (print first n char's)
  • head does not have a + option unlike tail [ce.lpi]
  • $head -c 5 f.txt     (display first 5 char's of file)
• tail (output the last part of file, last 10 lines by default)
  • -n n (display `number' of last n lines)
  • $tail -5 f.txt   (or $tail -n 5 f.txt )     (display last 5 lines of file)
  • $tail +3 f.txt     (show last 8 lines of 10-line file)
  • #tail -f grow.txt     (continuously monitor file in real-time; exit with ^C); %tail -7f x.txt   (continuously monitor, starting with last 7 lines; %tail -f -5 x.txt :gives error)
  • #tail -f /var/log/messages | more     (continuously monitor file; shows user login and logout)
• more (pagewise text-viewing program, deprecated in favour of less)
  • -n (show `number' of rows)
  • SPACE (`forward' one screenful) | b or ^B (`back' one screenful) | / (`search' pattern) | n (`repeat' last search forward) | . (repeat last command) | v (start `vi') | ' (goto beg'g of file; fwd apostrophe) | = (show line number)
  • $more -25 f.txt     (display 25 rows of file at a time)
• less (`less is not less than more')
  • -c (`clear' screen before display) | -i (`ignore' case; default case-sensitive) | -r (`raw' ctrl chars. to be displayed) | -s (`squeeze' multi blank lines into single one) | -V (`version')
  • SPACE (`forward' one screen) | ENTER (goto next line) b = ^B (`back' one screen) | f = ^F (`forward' one screen) | d = ^D (`demi' = half-screen advance) |
  • $less f.txt    
• file (`file type')
  • $file f.txt     (show the type of file, eg. ASCII)

c. File Search and Location : Finding, Searching and Locating Files

• find
  • -mtime +n|-n (modified time more than/less than n days) | -atime +n|-n (accessed more than/less than n days ago) | -name xpattern (filename) | -iname xpattern (case-Insensitive match) | -print (print to stdout) | -prune (omit certain dir's) | -size n (size in blocks, if `c' then in chars) | -type b|c|d|p|l|s|f (blk dev, char dev, dir, fifo/named pipe, sym.link, socket, plain file) | -exec (exec. cmd on each file) | -ok (confirm before exec)
  • $find . -name '*.txt'     (search current dir tree for files ending in txt)
  • %find . -name CVS -exec rm -rf {} \;
  • $find . -name "*.html"     (search current dir tree for html files)
  • $find /etc -type d -print     (show dir tree below /etc)
  • $find /dev -type f -mtime -7 -exec ls -l{};     (show device files modifed in last 7 days)
  • $find . -type f -name "f.txt" -print     (find files named f.txt from present dir downwards and print output to screen)
  • $find . -type d -name "mydir" -print     (find dir's named mydir from present dir downards and print output to screen)
  • $find . -size +30k     (search current directory tree for files larger than 30k)
  • $find . -type f -print |xargs grep train     (find files containing string train)
  • $find / -mtime 1 -print > /tmp/filelist.daily     (find files modified in last one day, and print to stdout; whence $tar -cv -T /tmp/filelist.daily -f /dev/rft0 can back up these files regularly)
  • $find . -type f -name "f.txt" -exec rm {} \;     (remove file f.txt; {} = placeholder for filename \; delimits generated cmds)
  • $find . -type f -name "*.htm" | xargs grep Iranica
• locate (list files in databases that match a pattern)
• slocate (`secure locate') uses daily updated DB, so faster than find, but less powerful
  • $slocate profile
• which (show full path of commands; analog of $man -w ls for man pages)
• grep (`Global Regular Expression Parser': search for lines matching a pattern; Kamran.133; suited for search within files)
  • -i (`ignore case' in the pattern) | -r (`recursive' searoh of all files in a dir and its subdir's)
  • $grep -r -l "x=\"hi bo\"" * | less     (search recursively for x="hi bo", printg only filenames not line contents)
  • $grep " Hi world " *.txt     (search all files ending in txt for string specified including blanks)
  • $grep -e '-some' *.???     (search all files with a three letters suffix for -some)
  • $grep -ri Samar mydir|less     (search all files in mydir and subdir's for string Samar, ignoring case, piping output to less)
• fgrep (`fast grep': search for lines matching a pattern, regex not permitted)
  • $fgrep myword *.txt     (search all files ending in txt for myword)
• egrep (`extended grep': permits complex regex, does not accept braced or tagged regex)
  • $egrep myword *.txt     (search all files ending in txt for myword)
• xargs (`execute arguments' : execute command lines from standard input)
  • $ find . -name '*.txt' | xargs grep myword     (find all files in full directory tree ending in text, piping the output to a match for myword)
• locatedb (`locate database')
• updatedb (`updates file name databases used by GNU locate)

d. File Permissions

• chmod (`change mode')
  • 2 ways exist of changing the mode:
    1. Symbolic mode (u=user, g=group, o=other, a=all); which cannot cover all possibilities, whence:
    2. Absolute mode (r=4, w=2, x=1).
    • $chmod 744 *.txt     (allow user full permission, group read and other read)
    • $chmod +x *.txt     (allow execution to all levels)
    • $chmod =r *.txt
    • $chmod ug+rwx f.txt     (allow user and group to read, write and execute f.txt)
    • $chmod g+rw,o+r f.txt     (, not ;! others: read only, group: read and write)
    • $chmod u+s xgroup (suid, 4000)
    • $chmod g+s xgroup (sgid, 2000)
    • $chmod o+t /tmp = $chmod 1777 /tmp (sticky bit on; for dirs only)
  • Relative Permissions :

    who a :all g :owner's group o :all others u :just the user

    operator + :add mode - :remove mode = :set mode absolutely

    permission x :execute r :read w :write s :set user ID bit t :set sticky bit

• chgrp (`change group')
  • $chgrp xgroup f.txt    
• newgrp (switch to `new group')
• chown (`change owner')
  • $chown samar:xgroup f.txt     (change ownership; note that original users cannot then do anything with the file!)
• umask (`user mask': set the digits to be subtracted from full permission set: 666 {files} or 777 {dir's})
  • $umask 027    
  • umask(user) = 002 (default) (user private groups; new files=664); umask(root) = 022 (default)

e. FHS (Fs Hierarchy Standard)

The linux fs is often referred to as having a tree structure, since dir's and sub-dir's branch off like limbs from the single root dir [kamran.138].

• /usr/src/linux/fs/ dir. lists the types of files supported by the kernel.
• If /dev/MAKEDEV exists then devices can be created manually as needed; MAKEDEV.local is required for local devices.

II. Text Processing

a. Text Editors

• pico (simple file editor with few commands, resembles pine email program)
  • -w (`word-wrap' disabled) | -v (view-only) | -s ispell (spell checker) | -x (eXclude keymenu at screen bottom)
  • ^X (save+`eXit') | ^J (`justify' format paragraphs) | ^T (`thesaurus' spell checker) | ^R (`read' file) | ^W (`where is' search) | ^^ (set `control caret' block marker) | ^K (`kut' text block) | ^U (`unkut' text block) | ^O (write to `output file')
  • $pico -s /usr/bin/ispell -w f.txt = $pico -s ispell -w f.txt     (edit f.txt usg alt spell-checker without wrapping)
• pilot (file browser program used with pico; $pilot . )
• sed (`stream editor')
  • ^ (beg'g of line) | $ (end of line)
  • $sed "s/^$//" < myfile     (change empty lines to empty lines) [stocker]
  • $sed -e '/^$/d' < myfile     (remove empty lines) [stocker]
  • $sed -e s/Hello/World/g < f1 > f2 (global replace)
• vi (`visual ex'): 3 Modes exist:
  1. Escape/Command Mode (enter via ESC)
     • h, l (left, right) | k, j (up, down)
     • ^f (`forward' one screen) | ^b (`backward' one screen) | ^l (redraw screen)
     • /myword (search fwd) | ?myword (search backwards) | n (continue search)
     • c (`change' text) | d (`delete') | ndd (delete n lines) | i (`insert' text) | o (`open line below current in insert mode) | O (`open line above current in insert mode) | p (`paste' text = copy) | r (`replace' single char) | R (enter `replace text' mode) | u (`undo' last change) | x (`excise' single char) | y (`yank' = copy text) | nyy (`yank' n lines into unnamed buffer) |
  2. Input/Insert/Append/Text/Edit mode (entered by typing `i`=insert/input or `a`=append)
  3. Command-Line/Line/Colon Mode (`:`)
     • :q! (`quit' without saving) | :w (`write') | :wq (`write and quit') | :wq! (force-write to read-only file)
     • :r f.txt or :%r f.txt   (`read'+insert external file into buffer)
     • %s (entire file searched)
     • :%s/world/Globe/g or :s/world/World/g (global `search' and replace)
     • :%s/^ / /g (replace lines beginning five spaces with one space)
     • :%s/\%/\#/g (`search' :global search, escaping special characters)
     • :g/^$/d (remove blank lines)
     • :1,$s/^[ ]*// (remove leading blanks from all lines)
     • :%s/^/ /g (prepend five blanks to each line; say after $fmt -w 70 -s lpi102_c21.html > x.html; )
     • :set number | :set nonumber | :set all (show all set parameters)
     • :g/^$/d or :%s/^$/d     (delete blank lines)
  • $vi +10 f.txt     (place cursor on 10th line)
  • ~/.exrc (vi run-command file, eg:):
    set number
    set errorbells
    set showmode
• vim (`vi iMproved' - syntax colorg); cf. $vimtutor
• emacs, xemacs : emacs makes use of two main keys: one control key (^) and meta key (ALT, denoted by `m')
  • ^X^C (`eXit') | ^S^X (`save'+ exit) | ^S (`search') | ^R (`replace') | ^X M (`mail') | ^C^C (send mail) | ^H (`help') | ^V (`vorwaerts' 1 screen) | mV (back 1 screen) | ^X U (`undo') | ^X^F (open `file') | ^C K (`kill') | ^SPACE (mark block) | mW (copy block to internal clipboard) | ^Y (`yank') | ^W (`water out' or cut text) | m< (jump to start of buffer) | m> (jump to end of buffer) | ^H t (tutorial) | ^H k<KEY> (help on key funcn) | ^H i (info) [kamran.Ch.14]
• joe (`joe's own editor'): A suite of five editors: joe, jstar, jmacs, rjoe, jpico
  • ^KH (`help') | ^KX (`eXit'+ save) | ^Y (`yank') | ^KB (begin `block') | ^KK (end block)
• spell : (spell checker)
  • $ spell f.txt     (lists wrong words only without correcting the original file; this is linux aspell script mimicking the original Unix spell)
  • $ ispell f.txt     (interactive spell checker, user simply enters number of closest choice from matched words, `quit' to quit; ispell can use personal dictionaries)
  • $ aspell -c f.txt or $ aspell check f.txt     (linux spell checker)
  • $ aspell --help | less     (linux spell checker help)
• gedit (GTK+ based text editor)
• kedit (KDE text editor)
• nedit
• gnotepad+ ( Foot > Programs > Applications > gnotepad+ )
• gvim (`Gnome vi iMproved') Foot > Programs > Utilities > gvim
• gxedit (`Gnome X Editor'; a front end for html files)
• xedit (simple text editor): - Foot > Programs > Utilities > gnotepad+ or $/usr/bin/X11/xedit
• xjed ( `X Joe's editor'): $xjed or Foot > Programs > Utilities > xjed

b. Text Utilities (GNU TextUtils Package)

• cat (simplest linux text editor; cf. text editor section)
• cmp (`compare' 2 files)
• comm (`compare' 2 sorted files line by line)
• csplit (`context split': split file into context-determined pieces)
• cut (`cut' from each line in file)
  • -s - blank (`squeeze' multiple blank lines') | -n (`number' all non-blank lines)
  • $cut -f1,5 -d: /etc/passwd     ( extract 1st and 5th fields of given file, using semicolon as delimiter; shows userid and name )
  • $cut -d : -f 1,6-7 /etc/passwd     ( extract 1st and 6th-7th fields of given file, using semicolon as delimiter; shows userid, home dir. and default shell )
• diff (`differentiate' between two files)
  • $diff f1.txt f2.txt
• expand (convert tabs into spaces)
• fold (wrap input lines to fit in specified width)
• fmt (`format')
  • -w n (`width') | -u (`uniform spacing')
  • $fmt -w 20 f.txt   (or $fmt --width=20 f.txt )     (width 20)
  • $fmt -u f.txt     (uniform spacing)
  • $fmt -w 70 -s lpi102_c21.html > x.html; ; use pico ^O to remove ^M etc., use vi to prepend blanks
  • $fmt is equivalent to resizing the Xwindow in pico and using ^L
• head (cf. FS Navigation section)
• join (`join' lines of two files on a common field; files which have something in common) (cf. paste)
  • $join f1 f2     ( join common lines )
• nl (`number lines')
  • -b a | pREGEX (`body-numbering': no. all lines or only lines that contain a match for REGEXP) | -i n (`increment' by no. n) | -n ln | rn | rz (`number format')
  • $nl f.txt     (number lines)
  • $nl -i 5 f.txt     (number lines with increment 5)
  • $nl -n rn f.txt     (number lines right-no'd)
• od (`octal dump' to stdout)
• paste (`paste' two or more files having nothing in common) (cf. join)
  • $paste f.txt g.txt     ( join two file columnwise )
  • $paste -d: f.txt g.txt     ( join using : as delimiter )
• pr (`print': prepare file for printing)
  • $pr f.txt     (print file fully formatted to stdout, the screen)
  • $pr -h "Samar's File" f.txt | lpr -Pdj2     (print file with heading `Samar's File' to printer named dj2 = deskjet2 )
  • $pr -4 -t l.txt     (print list in four columns, truncating header and footer)
• sort (`sort' file)
  • -b (ignore leading `blanks') | -u (`unique') | -f (`force' sort upper- +lowercase as if all uppercase) | -n (`numeric order') | -xn (sort by number x) | -r (`reverse') | -m (`merge') [lpi]
  • $sort f.txt     ( sort file )
  • $sort +1 l.txt     ( sort file, skipping first field; in case of a list firstname lastname this will sort by last name)
  • $sort +1 -2 l.txt     (skip one field before sorting, stop sorting after second field)
  • $du | sort -rn     ( largest files first )
  • $sort f.txt | mail -s "!" user@mars     ( sort and mail )
• split (`split large file into smaller files')
  • $split f.txt     (split file into default of 1000-line chunks with file names Xaa, etc. with default prefix = X )
  • $split -10 /etc/passwd X   or $split -l 10 /etc/passwd     (splits password file into files Xaa, Xab, Xac, etc of ten lines each; the original file can be restored using $cat X?? > full.txt)
• sum (print checksum and block counts)
• tac (inverse cate: concatenate and write files in reverse)
• tail (`inverse head': cf. FS Navigation section)
• tee (`tee': read from standard input and write to standard out- put and files)
  • $sort f.txt | tee f.sorted     ( sort file, sending output to f.sorted )
• tr (`translate' chars, `trail search')
  • -d (`delete') | -s (`squeeze' repeats)
  • GNU tr does not support System V syntax of [] for ranges; but GNU tr uses [] for character classes
  • $tr a-z A-Z < f.txt = $tr [a-z] [A-Z] < f.txt = $tr "[a-z]" "[A-Z]" < f.txt    (translate from upper case to lower case)
  • $tr -d 0-9 < f.txt > o.txt     (delete all numbers from file, writing to new file)
  • $tr -s x < f.txt     (squeeze repeated occurrences of x to one x)
  • $tr [:upper:] [:lower:] < f.txt     (convert to lower case using character classes)
  • $tr -d [:alpha:] < f.txt     (erase all alphabets in file)
  • $tr -d [:blank:] < f.txt     (erase all blanks in file)
• unexpand (convert spaces to tab)
• uniq (`unique': remove duplicates from a sorted file)
• wc (`word count')
  • -c (`characters' = byte count only) | -m (print only char count) | -w (`word' count) | -l (`line' count only) | -L (print length of longest line)
  • $wc f.txt     (count lines, words and characters of file f.txt)
  • $wc -w f.txt   (or $wc --words f.txt )     (count words in a file)
  • $wc -l f.txt     (count lines in a file)
  • $wc -c f.txt   (or $wc --chars f.txt )     (count characters in a file)

c. Printing

• pr (`print' files to std output)
  • $pr f.txt | less     (print files)
  • $pr -n f.txt     (print with numbered lines)
  • $pr -8 f.txt     (print file 8 characters wide)
• lp, lpr, lpq, lprm (`line printer' cmds)

d. Latex and Tex

• latex
• pdflatex
• tex
• xdvi
• dvips
• ghostview
• lyx - GUI front-end for latex, pdf and html files.
• ps2ps (convert between ps files) (cf ps2pdf, pdf2ps manuals)
  • $ps2ps -dLanguageLevel=1 f.ps g.ps
• xpdf (Portable Document Format file viewer)
  • Scan to pdf: Adobe Acrobat (not just Reader) > Import/Scan > SCAN_ACROBAT; Destination > New PDF Doc > Scan
  • psmerge: concat ps files.
  • $mpage -c|-4 f1.ps f2.ps > f.ps reportedly concats ps
• enscript : txt to ps
  • $enscript -2 -Ecpp -r -v -d xprinter xfile (reportedly prt src code)
  • $encript -2rG f.txt (reportedly nice txt file)
• pdcat (cf. www.pdf-tools.com); pdfpages )ki

III. Documentation

• man (`manual')
  • -w (where: only print location of man pages)| -k xkeyword (keyword)
  • /usr/man
    • /man1: shell commands.
    • /man2: system calls
    • /man3: libc calls
    • /man4: device definitions.
    • /man5: file format.
    • /man6: games
    • /man7: system files
    • /man8: root utils.
  • /usr/doc : third party software manuals; eg. /usr/doc/alsa-2.11/
  • /usr/share/doc/HOWTO: HOWTOs = http://www.tldp.org = linuxdoc.org
  • $man 2 nice
  • $man -t xinetd > f.ps   - convert man page to ps file.
  • $PAGER (usu. more or less)
• whatis (brief info)
• apropos
• whereis (shows executable path(s) )
• which (which dir. in $PATH first holds executable)
• --help (but not for third party packages, which install help files under /usr/doc)
• info (access help files beneath /usr/info)
  • man vs. info:
    • hyperlinks do not exist in man pages, but exist for info
    • info is more current than man
    • not all man pages are maintained
  • /usr/info
• www: LDP etc.

IV. System Commands

a. Process Management Commands

• ps (`process status': deflt: procs assoctd userid + term)
  • -e (`everything') | -u (show `user' processes) | -f (`full')
  • 1 <=; pid <= 32768; pid(init) = 1; uid(root) = 0
  • $ps     (display processes using default settings, sample output is:

      PID TTY STAT TIME COMMAND
    12623  p0 S<   0:00 -bash 
    12937  p0 R    0:00 ps 
    

    where first column represents process ID no., second the terminal, third the status (S-sleeping, R-runnable, T-traced/stopped, Z-defunct zombie, D-uninterruptible sleep) + additnal letters ( <-hi-priority proc, N-low-priority task, L-pgs locked into mem, W-no residt pgs), fourth the amount of system time used, and the login shell or primary shell [kamran.128].
  • $ps -ef | less     (write all processes)
  • $ps -u samar     (show samar's processes)
• pstree (`process status tree' hierarchy) $pstree -a
• top (`show all processes')
• gtop (`graphical top')
• sleep (`sleep' for a specified no. of seconds)
  • $sleep 10 &     (suspend for 10 seconds in bg)
• killall (terminate all processes by name/runng a cmd; no pid requd)
  • #killall -HUP inetd (re-reads from /etc/inetd.conf )
• kill
  • 1 = SIGHUP = HUP | 2 = INT = ^C | 3 = QUIT | 4 = ILL (illegal instr) | 6 = ABRT | 8 = FPE (floatg pt. exceptn) | 9 = KILL = SIGKILL | 15 = TERM (default) [man 7 signal]
  • $kill -9 27645     (definitely kill process ID 27645, which can be obtained from $ps)
  • %kill 786 = %kill -15 786 = %kill -TERM 786
  • $kill -2 `pidof newmail`     (kill all processes named newmail)
  • kill needs pid no.; killall needs process name
• bg ( resume suspended job in backgd after ^Z suspdd it)
  • if ^Z|^C not work, $stty -a
• fg (`put job into foreground') (eg. $fg 345)
• jobs (show running background processes)
  • $kill %3 (terminate job 3 from `jobs')
• at (execute job `at' specified time)
  • $at 7:30 < mail.job     ( execute commands given in a text file mail.job at 7:30; this task sends an email at 7:30 to abbas on the machine jupiter with f.txt as message body and specified subject)

    mail.job

    mail -s "Hi !" abbas@jupiter < f.txt

  • $at 11:53 < mpeg.job     (execute commands given in a text file mpeg.ftp:)

    mpeg.job

    ftp mm-ftp.cs.berkeley.edu > log anonymous abbas@ lcd /user2/abbas/bin/ cd pub/mpeg/play/ bin get mpeg_play-linux-elf.tar.gz bye

  • $atq     (at queue:show list of at jobs after executing at)
  • $atrm 4     (remove job in at queue)

  • $at 12:30
    at> date
    at> who
    at> ^D

• crontab (edit `cron table'; cf. `System Maintenance' chapter)
• env (list exported or `environment' vars only): env.var. = a useful data item stored by the system
  • $PATH=$PATH:/usr/local/bin; export PATH   (includes new directory into existing path)
• set (show env. vars + local vars.)
• su (`substitute user')
  • $su root (keep current env.vars)
  • $su - xuser (inherit xuser's env.vars., execute ~/.bashrc, ~/.profile )
  • $su -c xscript (exec cmd after asking for passwd)
• wait (await process completion) (eg. $wait 345)
• nice (`be nice': reduce priority of a job)
• renice (once a job is running, only renice can change its priority)
• nohup (put process in bg)
• batch (schedule a job for later execution, but unlike at, only when system load permits)
• watch ( monitor specified process output at regular intervals)
  • $watch date     (monitor using default period of 2 seconds, exit with ^C)
  • $watch -n 1 date     (update every 1 second)

b. System Status Commands (Time and Host-Related)

• hostname (display or change `host name')
  • $hostname     (show hostname)
  • %hostname saturn     (set host name from root account)
• domainname (display or change NIS `domain name')
  • $domainname     (show NIS domain)
• logname (show `login name')
• cal (show `calendar' for years AD 1 - AD 9999)
  • $cal     (show calendar of current month)
  • $cal 4 1731 > dt.txt     (show calendar of April, 1731 AD pipe to file)
  • $echo $TZ     (show timezone)
• date
  • $date "+ %H:%M"     (show time. eg 18:41)
  • $date "+%D"     (show date, eg. 06/26/01)
  • #date 0101130091     (set date from root to 01/01/91, 1:00 pm)
• tty (show terminal device)
• clear (`clear' screen)
• reset (`reset' screen)
• ulimit (show+set `user limits')
  • $ulimit -a     (show all user limits)
• install
• stty (`set terminal')
  • $stty -a     (show all settings)
  • $stty kill '^C'     (kill key)
  • $stty erase ^H     (set backspace to erase; ^H is the ASCII code generated by the <BACKSPACE> key)
  • $stty kill ^U     (kill key)
  • $stty intr ^C     (interrupt key)
  • $stty susp ^Z     (suspend key)
  • $stty sane     (restore to reasonable settings)

V. Internetwork + Communication Tools

a. E-Mail

• pine (`pine is not elm', `Program for Internet News and Email')
  • ^X (`exit': send a msg) | ^J (`justify', format paras) | ^T (`thesaurus' spell checker) [kamran.260]
  • ~/.pinerc     (pine initialization or run-command file)
  • ~/.signature     (signature file, automatically appended to each message)
• mail
  • $mail     (view mail, use v 12 to view message no. 12)
  • $mailx     (extended mail program available on some systems)
  • $mail abbas@hotmail.com     (send mail to given address)
  • $mail -s "hello samar" abbas@samarstan < f.txt     (send mail with given subject, using f.txt as body; useful for shell scripting)
  • ~/.forward     (forward emails)
  • ~/.mailrc     (mail configuration file)
• elm
• biff y|n (be notified if mail arrives and who it is from)
• xbiff (`xbiff')
  • $xbiff -update 10 -bg black -fg yellow -geometry 50x50-0+0 -volume 80   (places mailbox icon on upper RH corner; when mail arrives in /var/spool/mail, beep occurs + bg becomes yellow)
  • xbiff reportedly works over the network on Solaris/HPUX; supposedly if xbiff*checkCommand: ebiff -x exists in ~/.Xresources or ~/.Xdefaults for Solaris 2.6 and later.
• xmh
• xmailbox

b. Chatting

• write (`write' to logged-in user)
  • $write ummi     whence ummi must reply $write samar
  • $write samar tty03     (write samar on terminal tty03)
  • $write samar@venus.xly.com     (write across the internet)
  • Conditions
    • Login: User must be logged in.
    • Permission: User must have granted talk permission: $mesg y   .Entering $mesg n disables all input.
• motd, news (`message of the day' and news )
• wall (`write all': broadcast message to all users)
  • $wall "Hello from Samar Abbas"
  • Conditions
    • Login: user mustbe logged in.
    • Permission: user musthave granted talk permn: $mesg y  
      Entering $mesg n disables all input.
    • On some sys, only root can send a wall message usu. stored in /etc/wall
• finger
  • $finger samar
  • $finger abbas@unix.mit.edu     (finger across the internet)
  • $chfn (change your finger info)
  • ~/.plan : file executed by finger
• talk
  • $talk samar@webtech.com     (talk to samar across internet)
  • Conditions
    • Login: User must be logged in.
    • Permission: User must have granted talk permission: $mesg y  
      Entering $mesg n disables all input.
  • /etc/xinetd/talk; /etc/xinetd/ntalk: must contain line disable=no, else "Error on read from talk daemon: Connection refused. Press any key...": Default RedHat 7.0 `Custom' install has the line disable=yes .
• kibitz, screen, advise (spy on other terminal)
• echo (returns given msg)
  • $echo "Hello Samar"     (print to terminal)
  • $echo -e "Can you hear the Bell ? \07 "     (print to terminal, \7, \007 also work)
  • $echo -e "Enter Y or N : \c"     (remains on same line)
• crypt : % crypt mypasswd < f.txt > f.crypted ; % crypt mypasswd < f.crypted
• ssh (`secure shell': encrypt whole session, telnet replacemt)
  • $ssh iopb = $ssh iopb -l afsar = $xterm -e ssh iopb abbas & .
  • zircon:~$ scp abbas@iopb:~/papers/drafts/pap.html ~ = secure cp
  • Procedure for auto-logins:
    1. $ssh-keygen : generates new keys, overwrites old ones. Sample config (zircon 19.2.2002)

         [afs@zircon afs]$ ssh-keygen
         Generating public/private rsa1 key pair.
         Enter file in which to save the key (/world/afs/.ssh/identity): 
         /world/afs/.ssh/identity already exists.
         Overwrite (y/n)? y
         Enter passphrase (empty for no passphrase): 
         Enter same passphrase again: 
         Your identification has been saved in /world/afs/.ssh/identity.
         Your public key has been saved in /world/afs/.ssh/identity.pub.
         The key fingerprint is:
         a4:6e:98:94:2b:80:34:a1:4a:89:92:49:51:08:a1:e2 afs@zircon
       

    2. cp afs@zircon:~/.ssh/identity.pub --> afsar@iopb:~/.ssh/authorized_keys of server afs@iopb
    3. $ssh iopb -l afsar logged in without a password.

e. www

• telnet (remote login prog, deprecated for ssh as unencrypted) (hostname should exist in /etc/hosts)
• ftp
  • $ftp venus.ensindia.com = $ftp 198.100.11.15
  • ftp> !cmd (local shell) | macdef xmacro (def. macro) | $xmacro (execute macro xmacro def'd by macdef subcmd)
  • ascii (default type) | bin (binary type) | bell (sound bell after each transfer) | hash (print hash sign # per data block of 1024b transferred) | passive (transfer via data port; useful behind firewalls)
• netscape (`internet scape')
• lynx (fast txt-web browser, cannot disply frames)
  • $lynx http://www.google.com     (works for direct internet connection)
  • $lynx .     (browse home dir)
  • $lynx -source http://www.ibm.com/index.html > new.html &     (download file in background)
  • $http_proxy ="http://some.server.dom:port/"
    $export http_proxy
        (proxy server settings, other variables are ftp_proxy, gopher_proxy, then use $lynx http://www.google.com
  • o - options | q - quit
• links (fast txt web browser displayg frames)
• mozilla (excellent browser, = code base for NS)
  • ctrl + | ctrl - : magnify/microfy font size
  • ctrl f : find
  • ctrl q : quit
  • modern appearance: Edit > Prefs > Appearance > Themes > Modern
  • middle-clk opens links in tabs not new windows: check Edit > Preferences > Navigator > Tabbed Browsing > "Open Tabs instead of windows for Middle-click, ctrl-click or ctrl-enter on links in web pg"
  • open lks in new tab in bg w/o losg current window: also check Edit > Preferences > Navigator > Tabbed Browsing > "Load links in the background"
  • ctrl tab | ctrl pg down : cycle thro tabs
  • cp paste: select, ctrl c, rbutton (cygwin) | ctrl v (win)
  • ctrl h: history

    ---

  • mouse wheel: Edit > Prefs > Advced > Mouse Wheel
  • keywds: Edit > Prefs > Navigator > Smart Browsg
  • receipts: Edit > Prefs > Mail + Newsgroups > Return Receipts
  • Privacy + Security: Cookies (cookie stoppg), Images (dont load any imgs), Popup Windows (block unrequested popup windows), Forms (save form data), Passwords, etc.
  • set as deflt browser: Edit > Prefs > Navigator > Set Deflt Browser
  • keywords, eg. chicago careers, (http://wp.netscape.com/escapes/keywords)
  • RAR file support: Edit > Prefs > Navigator > Helper Apps > Mime Type = application/x-rar-compressed & Description = RAR File & Extension = rar, gz, tar & Open it with: C:\Program Files\WinRAR\WinRAR.exe (from http://www.rarsoft.com)
  • Chm (compressed html) file support: Edit > Preferences > Navigator > Helper Applications > New Type > MIME Type: application/x-html-compressed & Description: Compressed HTML File & Extension: chm & Open it with C:\WINNT\hh.exe
  • zip file support: Edit > Preferences > Navigator > Helper Applications > New Type > MIME Type: application/x-zip-compressed & Description: Winzip File & Extension: zip & Open it using the default application
  • ctrl r: reload, ctrl shift r: force reload
  • alt → | alt ← : fwd | back
  • ctrl q: quit
  • ctrl 6: irc chatzilla
  • ctrl 5: addr book
  • ctrl 2: mail + news
  • ctrl b: manage bkmarks, ctrl d: add pg to bkmarks
  • f11: full screen mode
  • ctrl w: close tab
• w3m (fast txt web browser)
• ncftp (improved ftp program; includes ncftpput, ncftpget)
  • $ncftp ftp://user@mars.ensindia.com     (start ftp, which will ask for password)
  • $ncftp ftp://user:pass@mars.ensindia.com     (login without password prompt)
  • Features
    • Command History
    • Command-Line Completion through <TAB> key
  • get -R mydir (`recursively' obtain whole dir tree under mydir using tarring) | put -R mydir (upload whole dir tree') | get -RT mydir (interactively obtain dir tree with individual file comparison and without tarring) | lmkdir mydir (`locally make dir') | lls (`locally list')
• wget (`web get' automatic site downloader or site sucker, cf. ftp://ftp.gnu.org/gnu/wget)
  • -r (`recursive' download of whole site) | -b (go into `bg') | -c (`continue' interrupted download of a large file) | -nc (`nonclobber': do not overwrite existing files)
  • wget --header "cookie: dla=1" --post-data "action=http://download.35mb.com/user/file.txt" http://download.35mb.com/user/file.txt -c or Curl curl -b "dla=1" -d "action=http://download.35mb.com/user/file.txt" http://download.35mb.com/user/file.txt -# -o file.txt
  • $wget -r http://skyper.tmag.de/oreilly/books     (recursive mode: downloads to default of 5 levels)
  • $http_proxy ="http://198.100.11.15:8080"; export http_proxy
        (proxy server settings, other variables are ftp_proxy, gopher_proxy, then use $wget http://www.ibm.com
  • $wget -r -nc -T 2700 --proxy=on http://skyper.tmag.de/oreilly/books     (wget in recursive, non-clobber mode ie. resume previously interrupted downloads, with timeout in 2700 seconds and forcing acceptance of proxy settings)
  • $wget -r -l 2 -nc -T 2700 --proxy=on http://skyper.tmag.de/oreilly/books     (as above, but only to two levels)
  • $wget -q ftp://ftp.bluebyte.com/demos/eng/extreme-assault/xa_demo.exe &     (download Extreme Assault quietly in background)
  • $wget -q ftp://3dgamers.in-span.net/pub/3dgamers/games/unrealtourn/utdemo348.exe &     (download Unreal Tournament quietly in background)
  • $wget -c -b -o iw.log ftp://ftp.zdnet.com/gs/simulation/iwar2/iwar2demo1.zip     (continue download of 207 mb Ind.War in background)
• rftp (`remote ftp': SOCKS proxy ftp client)
• gftp (`graphical ftp'): $gftp or Foot > Programs > Internet > gFTP
• xchat (IRC client) $xchat or Foot > Programs > Internet > X-Chat IRC Client

d. Generic Networking

• ping (`pkt internet groper' send ICMP (Inet Ctrl Msg Proto) ECHO_REQUEST packets to network hosts)
  • $ping 198.100.11.14     (test connection to given host)
  • $ping mars.venus.com     (ping using hostname)
• traceroute
  • $ /usr/sbin/traceroute 198.100.11.14
  • $ /usr/sbin/traceroute hotmail.com     (find route across network)
• rlogin (`remote login')
  • $ rlogin 198.100.11.14     (remote login)
  • $ rlogin -l user mars     (remote login)
  • $ rcp alpha.com:/home/f.txt f.txt     (remote copy)

VI. X Windows

a. Window Managers & Desktops

• twm - ( Tom's Window Manager or Tab Window Manager ) named after its author Tom LaStrange [Kamran].
• fvwm - (F(?) Virtual Window Manager) Author Robert Nation did not specify what f was; hence variously expanded to feeble, fantastic, freaky, (or some other f word) [greenfield,5.4] Versions: fvwm, fvwm2 (http://www.hpc.uh.edu/fvwm/)
• icewm - can emulate other OS's.
• mlvwm - (Macintosh like vwm) (http://www2u.biglobe.ne.jp/~y-miyata/mlvwm.html)
• olwm, olvwm (Open Look Window Manager, Open Look Virtual Window Manager) Desktops by Sun. [Kamran]
• mwm - (Motif Window Manager) Licence fee = $150; LessTif is free clone: (http://www.lesstif.org/)
• qvwm (http://www.qvwm.org) A Win95 lookalike.

• KDE (http://www.kde.org) A second generation desktop based on Qt toolkit.
• Gnome (GNU Network Object Model Environment) (http://www.gnome.org/) A second generation desktop. Based on the open source Gtk+ toolkit (http://www.gtk.org) , unlike KDE. Its default window manager is Enlightenment.

b. Files & Generic Commands

• startx (`start x windows')
• switchdesk (`swith desktop')
• xsetroot (`set background') [change bg color]
  • $xsetroot -solid gray
  • $xsetroot (/usr/X11R6/include/X11/cursorfont.h) -hand1 draped_box
• xsri (change display logo); cf. /etc/X11/xdm/Xsetup_0 for usage
• xset
  • $xset m 5 10  ^nbsp; (set mouse speed 5x faster and 10 pixels)
• xlsfonts (`text listing of all fonts')
• xfontsel (graphical `X font selector' preview)
• xload (display system load average)
• xmag (`x magnifier')
• xcpustate
• animate (display a series of images); eg. $animate f*.jpg
• ~/.xinitrc (`x initialization file') [ init file ]
  • Default: /etc/X11/xinit/xinitrc
  • Format : Most commands should be run in background, last client in the foreground, when it exits the window session exits.

    xclock &
    xsetroot -sold blue &
    xterm -name "Main Window" 
    

    The following reportedly works well: fvwm2 -cmd FvwmM4 -debug /etc/X11/AnotherLevel/fvwm2rc.m4

  • User-level change of desktop is possible: exec fvwm2 ; or exec twm .
• ~/.Xresources (`x resources') [ init file ]
  • Default: /etc/X11/xinit/xinitrc
• /etc/inittab (`initial table') : id:3:... (text-mode) should be changed to id:5... (X11 mode)
• /etc/X11/xinit/xinitrc - global default xinit file.
• /etc/sysconfig/desktop - Sets desktop; contains a line: DESKTOP="GNOME" Alternate possibilities include "KDE" and "AnotherLevel" (for fvwm2).
• /etc/X11/xdm/xdm-config (`xdm configuration file')
• /etc/X11/xdm/Xsetup_0 (`xdm configuration file') usu. starts xsetroot, xsri.

Switching between virtual consoles is possible using Ctrl+Alt+F1, Ctrl+Alt+F2, etc.

c. FS Tools

• xterm (`x terminal')
  • -bd (`border' color) | -fg (`foreground' color) | -bg (`background' color) | -fn (`font')
  • $xterm -fn `xfontsel -print` &     (font selector, using xcolorsel reported possible)
  • $xterm -g 80x24+0+0 -name "Samar Abbas"&     (new x terminal at 0,0, 80 digits wide, 24 lines high named as given)
  • $xterm -font "12x24" -fg cyan -bg black -title "My Email"   where font aliases obtained via xlsfonts list; possibly previewed using $xfontsel or /usr/lib/X11/fonts/misc and colors from /usr/lib/X11/rgb.txt
  • xterm -xrm "XTerm*background: Blue"
  • %xterm -e 'ssh root@saadi shutdown -h now; ssh root@rumi reboot'   (exec. multiple cmds)
• xwininfo
• rxvt ( `ouR xvt' ) (fast vt102 term emulator; faster than xterm as it uses less swap space)
• gnome-terminal : $gnome-terminal   or Panel > Terminal Icon
• kterm ( `Kanji Terminal Emulator'): $kterm   or Foot > Programs > Utilities > KTerm
• ~/.Xresources

  XTerm*font: 12x24
  

  followed by $xrdb -merge .Xresources to inform X server of changes (options $xrdb -load|remove|merge); for more variables cf. $editres clicking Commands > Get Widget Tree followed by clicking crosshair on the desired window (eg. xterm) to display the tree, then Command > Show Resource Box to see properties.

d. Personal Management: Personal Info, Date and Time

• gnomecal (`gnome calendar') $gnomecal = Foot > Programs > Applications > Calendar
• ical : $ical or Foot > Programs > Applications > Ical
• xbiff (`mail indicator')
• xclock
  • $xclock -chime -analog -update 1     (analog clock which rings once every 30min, twice on the h, showing a second hand updated every sec)
  • $xclock -geometry 80x80 &
• rclock (`rclock')
• wmclock (`WindowMaker window mgr clock')
• xdaliclock (fancy daliesque clock)
• gfontsel (`gnome font selector'): $gfontsel = Foot > Programs > Utilities > Font Selector
• gnomecard (Address book): $gnomecard = Foot > Programs > Applications > Address Book

e. Mathematical Aids

• xcalc [ x calculator ]
  • $xcalc
  • DRG: (Deg|Radian|Grad); 545 deg = 0.785 rad. | EE: exponential | ln: log(base e) | STO: store to memory | RCL: copy from memory to display | SUM: add display to memory | EXC: swap number on display with number in memory | CHS: change sign | INV: invert function | RS: roll stack downward [tackett.182]
• gcalc (gnome calculator): $gcalc = Foot > Programs > Utilities > Simple Calculator

f. Display

• $DISPLAY:
  • client$ xhost +|-|server | start winaxe if ms
  • server$ DISPLAY=client:0.0; export DISPLAY
• WinAxe: free sw; export linux displays to ms when WinAxe runs.
• CygWin: free Unix emulator on Windows