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Tue Nov 17 11:38:36 PST 2009

Contents


    Typical Unix Commands

      UNIX Commands beginning ABCD

    1. adb::command, a general-purpose debugger.
    2. apropos::command, locate commands by keyword lookup.
    3. ar::command, maintain portable archive or library.
    4. as::command, assembler.
    5. at::command, execute commands at a later time.
    6. awk::command, pattern scanning and processing language.
    7. banner::command, make posters.
    8. basename::command, display portions of pathnames.
    9. batch::command, execute commands at a later time.
    10. bc::command, arbitrary precision arithmetic language.
    11. biff::command, give notice of incoming mail messages, named after the programmers dog.
    12. cal::command, display a calendar.
    13. calendar::command, reminder service.
    14. cancel::command, send/cancel requests to an LP print service.
    15. cat::command, concatenate and display files.
    16. cc::command, C compiler.
    17. cd::command, change working directory.
    18. chmod::command, change the permissions mode of a file.
    19. chown::command, change owner.
    20. clear::command, clear the terminal screen.
    21. cmp::command, compare two files.
    22. col::command, reverse line-feeds filter.
    23. comm::command, select or reject lines common to two sorted files.
    24. compress::command, compress, uncompress files or display expanded files.
    25. cp::command, copy files.
    26. crontab::command, user crontab file.
    27. crypt::command, encode or decode a file.
    28. csh::command, shell command interpreter with a C-like syntax.
    29. csplit::command, split a file with respect to a given context.
    30. ctags::command, create a tags file for use with ex and vi.
    31. cut::command, cut out selected fields of each line of a file.
    32. date::command, print and set the date.
    33. dc::command, desk calculator.
    34. df::command, display status of disk space on file systems.
    35. diff3::command, 3-way differential file comparison.
    36. diff::command, display line-by-line differences between pairs of text files .
    37. du::command, display the number of disk blocks used .

      UNIX Commands beginning with EFGH

    38. echo::command, echo arguments to standard output.
    39. ed::command, text editor.
    40. edit::command, text editor (variant of ex for casual users).
    41. egrep::command, search a file for a pattern using full regular expressions.
    42. eject::command, eject media device from drive.
    43. ex::command, text editor.
    44. expand::command, expand TAB characters to SPACE characters, and vice versa.
    45. expr::command, evaluate arguments as an expression.
    46. factor::command, obtain the prime factors of a number.
    47. false::command, provide truth values.
    48. fgrep::command, search a file for a character string.
    49. file::command, determine the type of a file by examining its contents.
    50. find::command, find files.
    51. finger::command, display information about local and remote users.
    52. fmt::command, simple text formatters.
    53. ftp::command, file transfer program.
    54. getopt::command, parse command options.
    55. getoptcvt::command, parse command options.
    56. getopts::command, parse command options.
    57. grep::command, search a file for a pattern.
    58. head::command, display first few lines of files.
    59. hostname::command, set or print name of current host system.

      UNIX Commands beginning with IJKLMN

    60. kill::command, terminate a process by default.
    61. ksh::command, KornShell, a command and programming language.
    62. last::command, display login/logout information about users and terminals.
    63. ld::command, link editor for object files.
    64. lex::command, lexical analysis program generator.
    65. ln::command, make hard or symbolic links to files.
    66. login::command, sign on to the system.
    67. lp::command, send/cancel requests to an LP print service.
    68. lpstat::command, print information about the status of the LP print service.
    69. ls::command, list the contents of a directory.
    70. m4::command, macro processor.
    71. mail::command, read mail or send mail to users.
    72. mailx::command, interactive message processing system.
    73. make::command, maintain, update, and regenerate related programs and files.
    74. man::command, display reference manual pages; find pages by keyword.
    75. mesg::command, permit or deny messages.
    76. mkdir::command, make directories.
    77. more::command, browse or page through a text file.
    78. mv::command, move files.
    79. nawk::command, pattern scanning and processing language.
    80. nice::command, run a command at low priority.
    81. nl::command, line numbering filter.
    82. nm::command, print name list of an object file.
    83. nohup::command, run a command immune to hangups and quits.
    84. nroff::command, format documents for display or line-printer.

      UNIX Commands beginning with OPQR

    85. od::command, octal dump.
    86. pack::command, compress and expand files.
    87. passwd::command, change login password and password attributes.
    88. paste::command, merge same lines of several files or subsequent lines.
    89. pg::command, files perusal filter for CRTs.
    90. pr::command, print files.
    91. ps::command, display the status of current processes.
    92. pwd::command, working directory name.
    93. rcp::command, remote file copy.
    94. renice::command, alter priority of running processes.
    95. rlogin::command, remote login.
    96. rm::command, remove files or directories.
    97. rmdir::command, remove files or directories.
    98. rsh::command, shell, the standard, job control shell, and restricted.

      UNIX Commands beginning with STUVWXYZ

    99. script::command, make typescript of a terminal session.
    100. sed::command, stream editor.
    101. set::command, set and unset local or global environment variables.
    102. sh::command, shell, the standard, job control shell, and restricted.
    103. shutdown::command, close down the system at a given time.
    104. sleep::command, suspend execution for an interval.
    105. sort::command, sort and/or merge files.
    106. spell::command, find spelling errors.
    107. split::command, split a file into pieces.
    108. strings::command, find printable strings in an object or binary file.
    109. strip::command, strip symbol table, debugging and line number information.
    110. stty::command, set the options for a terminal.
    111. sum::command, print checksum and block count for a file.
    112. tabs::command, set tabs on a terminal.
    113. tail::command, deliver the last part of a file.
    114. talk::command, talk to another user.
    115. tar::command, create (tape) archives, and add or extract files.
    116. tbl::command, format tables for nroff or troff.
    117. tee::command, replicate the standard output.
    118. telnet::command, user interface to a remote system using the.
    119. test::command, condition evaluation command.
    120. tftp::command, trivial file transfer program.
    121. time::command, time a command.
    122. touch::command, update access time and/or modification time of a file.
    123. tr::command, translate characters.
    124. troff::command, typeset or format documents.
    125. true::command, provide truth values.
    126. tset::command, establish or restore terminal characteristics.
    127. tty::command, get the name of the terminal.
    128. umask::command, set file-creation mode mask.
    129. uname::command, print name of current system.
    130. uncompress::command, compress, uncompress files or display expanded files.
    131. unexpand::command, expand TAB characters to SPACE characters, and vice versa.
    132. uniq::command, report repeated lines in a file.
    133. unpack::command, compress and expand files.
    134. unset::command, set and unset local or global environment variables.
    135. users::command, display a compact list of users logged in.
    136. uudecode::command, encode a binary file, or decode its ASCII representation.
    137. uuencode::command, encode a binary file, or decode its ASCII representation.
    138. vedit::command, screen-oriented (visual) display editor based on ex.
    139. vi::command, screen-oriented (visual) display editor based on ex.
    140. view::command, screen-oriented (visual) display editor based on ex.
    141. vipw::command, edit the password file.
    142. w::command, who is logged in, and what are they doing.
    143. wait::command, wait for a process to finish.
    144. wc::command, display a count of lines, words and characters in a file.
    145. whatis::command, display a one-line summary about a keyword.
    146. whereis::command, locate the binary, source, and manual page files.
    147. who::command, who is on the system.
    148. whoami::command, display the effective current username.
    149. whois::command, Internet user name directory service.
    150. write::command, write to another user.
    151. yacc::command, yet another compiler-compiler.
    152. ypcat::command, print values in a NIS database.
    153. ypmatch::command, print the value of one or more keys from a NIS map.
    154. yppasswd::command, change your network password in the NIS database.
    155. ypwhich::command, return name of NIS server or map master.
    156. zcat::command, compress, uncompress files or display expanded files.

    . . . . . . . . . ( end of section Typical Unix Commands) <<Contents | End>>

  1. file_name::=any sequence of letters, digits, underscores, +. -, :, ., #,....
  2. directory_name::=file_name. A directory is a specially formatted file in UNIX so the sames names are used for directories and files.
  3. pathname::= relative_path_name | absolute_path_name.
  4. relative_path_name::=directory_name "/" directory_name "/" ... "/" filename. [ relative_path ]
  5. absolute_path_name::="/" relative_path_name | "~" "/" relative_path_name.
  6. shell_wild_card::="*" | "?" | "[" characters "]".
  7. punctuation::= ";" | "&" | "|" | "&&" | "||" | parentheses | brackets | braces | quotation_marks.
  8. CWD::=current working directory.
  9. relative_path::=The CWD is prefixed in front of relative paths.
  10. echo::command, output values of arguments.
  11. read::command, take input for reader and set variable equal to it.
  12. export::command, place shell variable and value into the environment.
  13. variable_name::= letter anynumber of letters and digits.
  14. show_the_value_of_a_variable::="echo " "$"variable_name.
  15. setting_a_shell_variable::= variable_name"="value". -- no spaces near the =!
  16. getting_a_shell_variable_from_the_user::="read " variable_name.
  17. adding_a_variable_to_the_environment::= "export " variable_name.
  18. case_statement::="case" expression "in" eoln case_body eoln "esac".
  19. case_body::= case ... .
  20. case::= pattern ")" commands ";;" eoln. Notice the double commas
  21. if_statement::="if" commands eoln "then" commands O( "else" commands ) "fi".
  22. O::=optional
  23. test_command::= "[" test_expression "]".
  24. commands::= a sequence of commands spearated by semicolons etc.
  25. eoln::= the end of line character or a semicolon.
  26. expression::=test_command | expr_command | ....
  27. pattern::= just like a wild card description of a file name.
  28. trap::command, sets an action to be carried out on reciept of one of a list of signals.
  29. fortune::program, prints out a pseudo fortune cookie.
  30. setting_a_end_of_shell_trap::="trap " "'" command "'" 0.
  31. asking_for_a_fortune_cookie::="/usr/games/fortune " options.

    List of UNIX Standard Directory Names

     wrk	working files
     tmp	temporary files that can be removed once used
     bin	binary files and executable scripts
     src	source code for programs
     lib	libraries: data for other programs to use
     adm	Administrative files
     etc	for unix system data files
     misc	miscelaneous files
     include	header files to be included in C & C++ program
     News	Used by tin and other newreaders
     Mail	Used by elm for handling mail
     mail	Used by pine for mail messages
     usr	Files need by users but owned by the system
     u	where we put home directories
     var	various variable administrative and temporary files
     sbin	shared binaries
     share	shared directories
     mail	for mail
     local	Things we put on the system
     spool	for things waiting to be processed

    UNIX Definitions

  32. mkdir::command, make_a_new_directory, make_a_new_path.
  33. cd::command, change_to_directory.
  34. make_a_new_directory(D)::=mkdir D.
  35. make_a_new_path(P)::=mkdir -p P.
  36. change_to_directory(D)::= cd D. Before D must be an executable directory. Afterwards the CWD is D.
  37. md::DOS_command=UNIX(mkdir).
  38. CWD::=current working directory.
  39. stty::command, set_a_key_to, sets the terminal to a particular input/output mode.
  40. export::command, places variable and value in the environment.
  41. set_a_key_to::= stty stty_option 'tap the key'
  42. option::=erase | quit | intr | kill | ... .
  43. erase::stty_option=erase, set_your_new_erase_key
  44. quit::stty_option=quit. set_a_key_to kill and force a dump of running process.
  45. intr::stty_option=intr. set_a_key_to interupt a process - CTRL/C is normal.
  46. kill::stty_option=kill. set_a_key_to erase every thing you've typed.
  47. set_your_new_erase_key::= stty erase 'tap the key'
  48. set_the_terminal_environment(t)::= TERM=t; export TERM
  49. check_the_terminal_environment::= following
     			echo $TERM
  50. TERM::variable, put in the environment to indicate the kind of terminal you are thought to be using.
  51. TERMCAP::variable, containing a list of terminal capabillities
  52. termcap::=terminal capabilities. These were in "/etc/termcap" but some are also encoded in a library "terminfo" file in /usr/lib/terminfo/.
  53. terminfo::=/usr/lib/terminfo -- a directory of directories that contain an encoded form of terminal capabillities.
  54. capabillities::= things that a terminal can do like erasing a character or moving the cursor to the left.
  55. terminal::hardware=a device that is at the end (terminus) of a piece of wire that leads to a computer.
  56. environment::=a set of variable and values that are shared with programs that are loaded by the shell into the program that are used to describe the user's situation.

    UNIX Shell and Environment variables

  57. export::command, export_command.
  58. variable::=identifer |number | ....
  59. value::=a_string_of_characters.
  60. For V:variable, value(V)::string = $V.
  61. identifier::=a letter followed by zero or letters and digits.
  62. number::=one or more decimal digits.
  63. set_shell_variable::= variable=expression.
  64. set_environment_variable::=set_shell_variable; export variable_name.
  65. export_command::="export" variable_name...
  66. temporary_variable_for_program::=variable=expression program_name arguments.
  67. call_subshell::= ( commands ).
  68. expression::=value | $ variable | 'any_string' | "string_with_wild_cards" | reversed_quote any_command_that_produces_some_output reversed_quote.

    UNIX Working Directories

  69. HOME::variable=the directory to which you are logged in.
  70. CDPATH::variable=used to list directories you wnt to cd to in the Korn shell.
  71. cd::command=change directory.
  72. PS1::variable=primary prompt string.
  73. PS2::variable=secondary prompt string.

    What the UNIX Shell Does - details

  74. set::command, sets shell options, set_shell_options.
  75. echo::= echo item...
  76. <<::redirection, here_document.
  77. set_shell_options::= set -options.
  78. here_document::= << end_of_document_sentenel.
  79. USER::=an environment variable nearly always set to the user's login id on login.
  80. For variable V, $V ::=the value of variable with name V.

    UNIX Commands Done Quicker

  81. erase_word::=CTRL/U.
  82. erase_line::=CTRL/X.
  83. see_line_so_far::=CTRL/R.
  84. CTRL::=indicates that the CTRL is to be held down while the following key is tapped.
  85. Bourne_shell_for_loop::=for variable in list ; do commands; done.
  86. Bourne_shell_for_each_argument_loop::=for variable ; do commands; done.
  87. Bourne_shell_while_loop::=while commands ;do commands; done. Repeats the loop until one of the first sequence of commands fails.
  88. commands::= command;command;...
  89. list::= a space separated list of words and strings.
  90. variable::=any normal shell variable.
  91. enter_korn_shell_edit::=ESC
  92. For line E, here_document::= command <<E eol ... eol E eol.
  93. eol::=end of line.
  94. list_tail_of_file::=tail -number_of_lines file.
  95. list_files::=ls -ls_options.
  96. number_of_lines::=any decimal number.
  97. file::=a name of a file.
  98. ls_options::= a list of letters and digits.
  99. search_for_a_pattern_in_some_files::= egrep pattern files...
  100. pattern::=a description of lines of interest, [ 26.patterns.html ]
  101. sort::command, the UNIX system sort - fast, general purpose, comprehensive with many posible options and features.
  102. sort_and_make_unique::=sort -u.
  103. global_substitute_in_vi::= :%s/pattern/replaced_by/.
  104. replaced_by::=a string.
  105. s::ex_command, substitution.
  106. ex_command::=in vi you can type a colon and then any command of the ex editor.
  107. ex::=the extended UNIX editor.
  108. vi::=the visual UNIX editor, actually a visual interface arround ex.

    UNIX Job Control

  109. jobs::command, show_me_my_jobs.
  110. show_me_my_jobs::= jobs.
  111. job_number::= number listed by the show_me_my_jobs command in square brackets. PID is a different number given to a job that is unique to the whole system. Job numbers are unique to the shell running them.
  112. fg::command, run_job_on_my_terminal.
  113. bg::command, run_job_in_the_background.
  114. run_job_on_my_terminal::= fg %job_number.
  115. run_job_in_the_background::= bg %job_number.
  116. kill_job::= kill %job_number.
  117. terminate_job_with_extreme_prejudice::=kill -9 %job_number.
  118. tell_job_that_I_ve_Hung_UP::=kill -HUP %job_number.
  119. kill::command, send_signal_to_process.
  120. kill_command::= send_signal_to_process.
  121. send_signal_to_process::=kill -signal process_identifier.
  122. PID::=process_identifier.
  123. process_identifier::=number found in the output of ps command in the PID column that uniquely identifies every job running on a system.
  124. signal::=number in range 0 to 15 | HUP | QUIT | KILL | TSTP | ...
  125. ps::command, list_my_processes | list_users_processes |list_all_processes |...
  126. list_my_processes::=ps.
  127. list_users_processes(user_id)::= ps -u user_id.
  128. list_all_processes::most_UNIX= ps -elf.
  129. list_all_processes::BSD_UNIX= ps aux.
  130. vi_writes_automatically::vi_command= :set autowrite eoln.
  131. stop_background_jobs_on_output::=stty stopped.
  132. let_background_jobs_output_on_my_screen::=stty -stopped.

    UNIX Redirection

  133. redirect_input_to_file::= < file.
  134. redirect_output_to_file::= > file.
  135. redirect_output_to_end_of_file::= >> file.
  136. redirect_input_to_come_from_here::= << end_of_input_sentinel.
  137. pipe_output_from_one_command_to_input_of_another::= command1|command2.
  138. run_commands_in_a_subshell::= ( commands ).
  139. run_command_in_background::= command&.
  140. treat_list_of_commands_as_one_command::= {commands}.
  141. split_the_output::=tee filename | tee -a filename.
  142. tee::command, split of input into a file and also pass it to the output.
  143. null::dev=a virtual device that is always empty and acts as a bottomless sink for unwanted output.
  144. the_empty_file::=/dev/null.

    UNIX UNIX Filesystems

  145. path::= absolute_path | relative_path.
  146. absolute_path::= / relative_path.
  147. relative_path::= file_or_directory_name | directory_name / relative_path.
  148. directory_name::= this_directory | parent_directory | my_home_directory | home_directory(user_name) | word.
  149. this_directory::= "." .
  150. parent_directory::= ".." .
  151. my_home_directory::= "~" .
  152. home_directory(U)::= ~U.
  153. file_or_directory_name::=word.
  154. user_name::= 1..8 alphanumeric characters found as the first field in a line in the /etc/passwd file.
  155. word::= any identifier.
  156. cd::command, change_directory.
  157. change_directory::syntax= cd path.

    UNIX Files

  158. wildcard::=a character that in some context indicates a set of possible chracters or strings.
  159. zero_or_more_chars::wildcard="*".
  160. any_char::wildcard="?".
  161. any_one_of::wildcard=[list of chars and ranges].
  162. remove_file::=rm options filenames
  163. list_info_about_files::= ls options filenames
  164. grep::command, Global regular expression print::=Search files. [ 27.searches.html ]
  165. list_files_that_have_a_string::= grep -l string files
  166. show_files_andlines_that_have_string_in_them::= grep string files
  167. ls::command, list information about files, list_files.
  168. egrep::command, extended pattern search, list_files_that_contain_string.
  169. list_files::=ls ls_options files
  170. ls_options::= - ls_option ...
  171. ls_option::= t | r | R | l | F | d | A | a | q | ...
  172. t::ls_option=time of last change order
  173. r::ls_option=reverse order
  174. R::ls_option=recursively down all subdirectories etc
  175. l::ls_option=long -- lots of info
  176. F::ls_option=Flag executables+directories+symbolic links.
  177. a::ls_option=all files and directories including dot-files.
  178. q::ls_option=make invisible characters a question mark in listing
  179. files::= empty | file | file file ...
  180. file::= name_of_a_file| name_of_a_directory | something_with_wildcards
  181. this_process_s_uniqe_identifier::=$$.
  182. list_files_that_contain_string::= egrep -l string *.

    UNIX Find

  183. find::command, searches a directory subtree for files and directories meeting more or less complex criteria and processes them in various optional ways, find_files_under_directory_fitting_conditions.
  184. find_files_under_directory_fitting_conditions::=find directory condition -print,
  185. find_files_under_directory_fitting_conditions_and_do_things::=find directory condition do_things,
  186. directory::=any name of a directory or a file name, [ path in 14.filesystems ]
  187. condition::= disjunction,
  188. disjunction::= conjunction -o conjunction...,
  189. -o::find_option= or,
  190. conjunction::= primitive_condition ..., -- one or more in sequence.
  191. primitive_condition::= \( disjunction \) | ! simple_condition,
  192. simple_condition::= - option arguments_for_option,
  193. option::= name | perm | type | user | group | size | inum | atime | mtime | ctime | newer | exec | ok | print.
  194. exec_option::find_option= -exec unix_command \;.
  195. symbol_for_for_found_file_name::= "{}"
  196. end_of_exec_symbol::= \;

    UNIX Names, copies, links and files

  197. cp::command, copy_file.
  198. mv::command, move_link.
  199. rm::command, remove_file.
  200. ln::command, make_link_to_a_file.
  201. inode::=information node -- the fundamental block of data that is collected together by UNIX to form files.
  202. directory::=a file that has a special layout that links file names with inode numbers and other information.
  203. copy_file::=cp copy_options filename filename | cp filename ... directory_name.
  204. copy_options::= none | recursive | force.
  205. recursive::= -r. -- on most systems.
  206. filename::= normal name of file.
  207. filename::= See http://www.csci.csusb.edu/dick/cs360/notes/01.intro.html#file_name.
  208. directory_name::=name of a file that is a directory.
  209. make_link_to_file::command= ln ln_options existing_file newfile | ln options existing_file ... directory_name.
  210. existing_file::=filename. & does exist.
  211. newfile::=filename & does not exist.
  212. ln_options::= none | symbolic | force | symbolic_and_force.
  213. symbolic::= -s.
  214. force::= -f. Overwrite existing with out complaint or warning.
  215. symbolic_and_force::= -sf.
  216. remove_link_to_file::= rm filename ... | rm -i filename ... | rm -r filename ... | ... . [ Definitions in 23.delete ]
  217. move_link::= mv move_options filename newfilename | ... -- actually a the result of linking to new and removing the old!
  218. move_options::=force|none.
  219. tar::command, tape_archive_processor
  220. tape_archive_processor::= create_archive | extract_from_archive | ...
  221. create_archive::= tar cf filename directory_name.
  222. extract_from_archive::= tar xf filename directory_name | verbose_extract.
  223. verbose_extract::= tar xvf filename directory_name.
  224. none::options= nothing, nada, leave blank, null, empty string, ...

    UNIX Security and Privacy

  225. ls::command=list files command. [ list_ownerships_etc ]
  226. chmod::command=change permitted modes for a file. [ change_permissions ]
  227. umask::command=set_default_permissions.
  228. list_ownerships_etc::=ls -l files.
  229. set_default_permissions::=umask three_octal_digits.
  230. three_octal_digits::=octal_digit octal_digit octal_digit.
  231. change_permissions::= chmod new_mode files.
  232. new_mode::=three_octal_digits | who op what,
  233. who::= optional u optional g optional o | a
  234. op::= + | - | =.
  235. what::=any number of r w x X s t.
  236. octal_digit::= 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7.
  237. files::=a list of file names separated by white spaces - often the result of wildcard expansion.
  238. setuid::=set user identity.
  239. setgid::=set group identity.

    Deleting things in UNIX

     	trash files...
  240. rm::command=remove_some_files | remove_files | remove_a_directory_tree.
  241. rmdir::command=remove_empty_directories.
  242. mv::command=put_things_in_a_trashcan | ... .
  243. find::command=find_all_trashcans | ... . [ 17.finding.html ]
  244. remove_files::= rm list_of_files.
  245. remove_some_files::= rm -i files.
  246. remove_a_directory_tree::=rm -r directories.
  247. remove_empty_directories::=rmdir directories.
  248. put_things_in_a_trashcan::=mv files .trashcan.
  249. find_all_trashcans::=find . -name .trashcan -print.
  250. files::=list of one or more file name separated by spaces. -- can be generated by a wild card.
  251. df::command=disk_free.
  252. du::command=disk_usage.

    Showing what is inside a file on UNIX

  253. more::command, see_one_screen_at_a_time.
  254. less::command, see_one_screen_at_a_time.
  255. pg::command, see_one_screen_at_a_time.
  256. cat::command::, concatenate_files.
  257. od::command, octal_dump | hexadecimal_dump | character_dump.
  258. file::command, find_out_type_of_data_in_files.
  259. sed::command, edit_a_stream_of_lines.
  260. tail::command, look_at_the_end_of_a_file.
  261. see_one_screen_at_a_time::= more files | less files | pg files.
  262. concatenate_files::=cat files | cat -cat_options files.
  263. cat_options::= v | n | t | ...
  264. make_non_printing_visible::cat_options= v.
  265. number_the_lines::cat_options= n.
  266. octal_dump::=od files.
  267. hexadecimal_dump::=od -x files.
  268. character_dump::=od -c files.
  269. find_out_type_of_data_in_files::= file files.
  270. edit_a_stream_of_lines::= sed.
  271. look_at_the_end_of_a_file::= tail file | tail tail_options files.
  272. tail_options::= +number_lines_skipped | -number_of_lines_shown ...
  273. reversed::tail_options= r.
  274. watch_a_file_grow::tail_options= f.
  275. number_of_lines_skipped::=any decimal number.
  276. number_of_lines_shown::=any decimal number.
  277. files::=list of one or mire filenamess separated by white space.
  278. file::=name of a file

    Regular Expressions

    UNIX For Programmers

    Syntax

      UNIX Commands

    1. vi::command, visual editor.
    2. ed::command, the original editor.
    3. ex::command. the extended editor. command mode in vi as well.
    4. grep::command. short for g/RE/p in ed. search_program.
    5. egrep::coomand. An extended grep -- more options and often faster. search_program.
    6. fgrep::command. Fixed grep - search for strings with no magic. search_program.
    7. expr::command. Can be used to test to see if an argument matches a pattern in a shell script: [ expr in 45.scripts ]
    8. find_lines_in_file::= search_program options pattern files.
    9. search_program::= grep | egrep | agrep.
    10. find_lines_with strings_in_files::= fgrep options string files.
    11. Start_edit_at_line_with_string::= vi +/"pattern" file | ex +/"pattern" file.
    12. grep_options::= -v | -w | -i | -l | -c | any combination | ...
    13. magic::=having RE in searches in an editor.
    14. editor::= vi | view | ed | ex | edit.
    15. call_an_editor_to_crete_or_change_a_file::= editor filename.

      Searching in UNIX editors

    16. search_forward::= /pattern/
    17. search_backwards::=?pattern?

      Global commands in ed/ex in UNIX

    18. do_it_to_all_lines_that_match::= g/pattern/ed_command.
    19. ed_command::=delete | insert | move | substitute | join | read | write | ...
    20. ex_command::=just like ed ony more of them.

      Global commands in vi

    21. do_it_to_all_lines_that_match_in_vi::= :g/pattern/ex_command.
    22. Symbols_used_in_patterns::=following

      Patterns in UNIX

    23. pattern::= optional(start_of_line_anchor) main_pattern optional(end_of_line_anchor).
    24. main_pattern::=any_number( (any_char | set_of_chars | normal_char | escaped_char) optional(any_number_of_the_previous))).
    25. start_of_line_anchor::= ^
    26. end_of_line_anchor::= $
    27. set_of_characters::= [ #( character | character - character ) ].
    28. any_character::= .
    29. any_number_of_the_previous::= *

      Regular Expressions

    30. RE::=regular_expression.
    31. regular_expression::=a regular expression use sequence+selection+iteration to express a set of possibillities.
    32. REs::=plural of RE

      Extended REs for egrep

    33. or::= |
    34. option::= ?
    35. one_or_more_of_the_previous::= +
    36. n_thru_m_repetitions::= \{ n, m \}
    37. n_repetitions::= \{ n \}

      REs in ex/vi

    38. start_of_a_word::= \<
    39. end_of_a_word::= \>

    . . . . . . . . . ( end of section Syntax) <<Contents | End>>

  279. grep::command, global regular expression print.
  280. egrep::command, extended grep.
  281. agrep::command. Arizona grep.
  282. fgrep::command, fixed string grep.

    Comparing UNIX Files

  283. make::command, automates compilation, linking, and other repeitive processes, $make_something.
  284. diff::command, find_differences_between_2_files, apply_a_delta_file.
  285. ex::command. Calls the extended editor. use_a_delta_file.
  286. make_something::=make something.
  287. something::=filename... .
  288. filename::= See http://www.csci.csusb.edu/dick/cs360/notes/01.intro.html#file_name.
  289. makefile::= how_to_make_something ...
  290. how_to_make_something::= target:sources actions_that_make_target_from_sources... eoln.
  291. actions_that_make_target_from_sources::= eoln tab command.
  292. eoln::=end_of_line.
  293. tab::=a real tab character... spaces will not work.
  294. find_differences_between_2_files::=diff options filename filename.
  295. diff_options::= none | -e
  296. make_a_delta_file::= diff -e oldfile newfile >deltafile.
  297. apply_a_delta_file::=ex - oldfile <deltafile.
  298. oldfile::=filename.
  299. newfile::=filename.
  300. delatafile::=filename.
  301. cmp::command.
  302. bytewise_comparison::= cmp filename filename.
  303. comm::command.
  304. compare_alphabetical_lists::=comm comm_options filename filename.
  305. comm_options::= - ( 1 | 2 | 3 | 12 | 13 | 23 ).

    Why use a program to compare files

    UNIX text handling tools

     		~dick/bin/prep
     		~dick/bin/concordance
     		~dick/bin/textanal
     		~dick/bin/prep

    Extra on some system

     		diction name_of_your_text_file
  306. spell::command. Outputs words from input that aren't in the dictionary.
  307. ispell::freeware. Interactive spell checker.
  308. wc::=word_count_etc.
  309. word_count_etc::= count_everything | count_line | count_words | count_characters.
  310. count_everything::= wc filenames...
  311. count_words::= wc -l filenames...
  312. count_lines::= wc -w filenames...
  313. count_characters::= wc -c filenames...
  314. filenames::=list of names of existing files searated by spaces.

    Vi Tips and techniques

      Beginners start here

      [ List of Vi Commands ]
      	:w	Write this file
      	:n	Next file
       	:e<file>	Edit file
       	:e#	Edit the other file
       	:e!#	Edit the other file and forget my changes to this file
       	cut	"cd<something>
       	copy	"cy<something>
       	paste	"cp		pastes after cursor
       	paste	"cP		pastes before cursor
       	.exrc
      	ex	the extended editor that vi is an interface to
       	  rc	read commands
       	!}br				word wrap paragraph(CSUSB only)
       	!Gsort|uniq -c|sort -nr		list and count words in file
      	!4!spell<enter>u		spell check 4 lines
      	!'astats			work out statistics...
       		:!generate_index_file >index.html &
      		:ab<enter>

      Syntax of Vi commands

        Notation

      1. c::=character.
      2. ctrl(k)::=tapping the k key with the Control shift held down.
      3. dot::= .
      4. period::= .
      5. eoln::=tap the Return or Enter key
      6. eoln= End-of line.
      7. esc::=the Esc character
      8. letter::="a".."z" | "A".."Z".
      9. n::=decimal_number.
      10. text::=any series of characters with no Esc in it unless prefixed by a ctrl V.
      11. SP::=space.
      12. BS::=Back_space.

        List of Vi Commands

      13. vi_repeat_command_n_times::= n vi_command,
      14. vi_append_after::= a.
      15. vi_add_after_end_of_line::=A.
      16. vi_move_back_a_word::=b.
      17. vi_move_back_a_big_word::=B.
      18. vi_change_something::= c movement replacement_text esc
      19. vi_change_rest_of_line::= C replacement_text esc
      20. vi_change_one_line::= cc replacement_text esc.
      21. vi_change_n_lines::= c n c replacement_text esc.
      22. replace_ment_text::=text.
      23. vi_cut_command::= double_quote buffer_id vi_delete_something,
      24. vi_delete_something::= d movement. [ vi_delete_character ]
      25. vi_delete_rest_of_line::=D.
      26. vi_delete_whole_line::= dd.
      27. vi_delete_n_lines::= d n d.
      28. vi_move_to_end_of_word::=e.
      29. vi_move_to_end_of_big_word::=E.
      30. vi_move_to_find_char_in_line::= f c.
      31. vi_move_to_find_previous_char_in_line::= F c.
      32. vi_go_forward_a_screen::= ctrl/F,
      33. vi_move_forward::=ctrl/F,
      34. vi_go_to_line_n::= n G
      35. vi_move_to_line::= n G
      36. vi_go_to_last_line::= G,
      37. vi_move_to_last_line::= G,
      38. vi_give_me_information_on_this_file::=ctrl/G | :f eoln
      39. vi_move_back_a_space::= h | BS.
      40. vi_insert_text::= i inserted_text esc.
      41. inserted_text::=text.
      42. vi_insert_a_start_of_line::= I inserted_text esc.
      43. vi_move_down::=j
      44. vi_move_to_start_of_text_on_next_line::=eoln| + .
      45. vi_join_lines::=J.
      46. vi_move_up::=k.
      47. vi_move_up_to_start_of_text_on_previous_line::= -.
      48. vi_move_forward::= l | SP.
      49. vi_mark_this_point::= m letter.
      50. vi_move_to_next_string::=n.
      51. vi_move_to_next_string_backwards::=N.
      52. vi_open_line_below::=o inserted_text esc.
      53. vi_open_line_above::=Oinserted_text esc.
      54. vi_paste_last_delete_after::=p.
      55. vi_paste_last_delete_before::=P.
      56. vi_paste_buffer::=double_quote buffer_id (p | P).
      57. vi_paste_last_but_n_delete::=double_quote n (p|P).
      58. vi_quit_visual::=Q.
      59. vi_replace_a_char::= r c
      60. vi_replace_string::= R text esc.
      61. vi_substitutes::=s something
      62. vi_move_to_char::=t c.
      63. vi_move_to_char_backwards::=T c.
      64. vi_undo::=u.
      65. vi_Big_undo::=U.
      66. vi_undo_everything::= :e! eoln.
      67. vi_redo::= dot .
      68. vi_move_over_word::=w.
      69. vi_move_over_big_word::=W.
      70. vi_delete_char::=vi_cross_out|vi_cross_out_previous.
      71. vi_cross_out::=x.
      72. vi_cross_out_previous::=X
      73. yank::=copY.
      74. copY_into_buffer::= double_quote buffer_id vi_copy_command,
      75. buffer_id::= letter
      76. vi_copY_something::= y movement.
      77. vi_copY_line::=yy.
      78. vi_go_to_sleep::=ZZ
      79. vi_line_commands::= : ex_command.
      80. vi_quit_and_no_save::= q!
      81. vi_search_forward::= / vi_regular_expression,
      82. vi_search_backward::= ? vi_regular_expression, [ 26.patterns.html ]
      83. vi_shift_line_left::= <<,
      84. vi_shift_line_right::= >>,
      85. vi_shift_n_lines_left::= <n<,
      86. vi_shift_n_lines_right::= >n>,
      87. vi_shift_something_left::= <movement,
      88. vi_shift_something_right::= >movement,
      89. vi_shell_escape::= vi_pipe_thru | ex_shell_escape,
      90. vi_pipe_thru::= vi_pipe_line | vi_pipe_n_lines | vi_pipe_something,
      91. ex_shell_escape::= :! shell_command,
      92. vi_pipe_line::= !!,
      93. vi_pipe_n_lines::=!n!,
      94. vi_pipe_something::= ! movement.
      95. vi_go_to_column_n::= n vertical_bar,
      96. vi_go_to_first_column::=0.
      97. vi_go_to_first_nonwhitespace::= ^
      98. vi_go_to_last_char_in_line::= $.
      99. vi_move_to_column_n::= n vertical_bar,
      100. vi_move_to_end_of_paragraph::= }.
      101. vi_move_to_first_column::=0.
      102. vi_move_to_first_non_whitespace::= ^
      103. vi_move_to_last_column::=$.
      104. vi_move_to_marked_character::=`
      105. vi_move_to_marked_line::='
      106. vi_move_to_matching_parenthesis::=%.
      107. vi_move_to_start_of_paragraph::= {.
      108. vi_word_wrap_the_whole_file::= 1G!Gbr eoln.
      109. movement::= any number followed by any vi command with "move" in above list,
      110. movement::=n single_movement.
      111. single_movement::= h | j |k | l | + | - | Fc|fc|tc|Tc G | SP | BS | { | } |....
      112. c::=any character

        The Vi Alphabet

      113. vi_command::=many including the following

        Some vi Line mode/ex commands

      114. ex_command::= address action,
      115. ex_actions::=following
        • a::ex_command, append upto line with a single . on it
        • d::ex_command, delete
        • e::ex_command, edit file
        • f::ex_command, which file name?
        • i::ex_command, insert before the line
        • j::ex_command, join lines
        • l::ex_command, list (show tabs and eolines)
        • m::ex_command, move lines
        • q::ex_command, quit
        • r::ex_command, read file in
        • s::ex_command, Substitute: s/old_pattern/new_string/flags
        • u::ex_command, Undo
        • vis::ex_command, Visual mode
        • w::ex_command, Write file
        [ 33.ed+ex.html ]
      116. address::= range | line | global | all_lines,
      117. all_lines::=%.
      118. this_file::= %.
      119. range::= line,line,
      120. global::= g search, vsearch,
      121. line::=search | n | place ( + | - ) n | search (+|-) n,
      122. place::= here | end_of_file,
      123. here::= dot
      124. end_of_file::= $
      125. search::= forwards|backwards
      126. forwards::= / pattern /,
      127. backwards::= ? pattern ?,
      128. ex_substitute_command::=addresss/pattern/replacement/flags,
      129. pattern::= [ 26.patterns.html ]
      130. replacement::=string with & and \1,\2,\3,... replaced
      131. flag::= any_number_of( c | g | p ), -- confirm, global, print.

      . . . . . . . . . ( end of section Syntax) <<Contents | End>>

    1. map::vi_ex_command, defines map from keys to commands.
    2. unmap::vi_ex_command, removes meaning of key.
    3. map_key_to_command::=map key commands.
    4. key::= a single key. prefix some control characters with CTRL/V.
    5. commands::=any sequence of vi commands, but prefix some control characters with CTRL/V.
    6. vi_ex_command::=in vi command mode tap the colon(:) key before the command and tap the return after the end.
  315. EMACS::=Editing Macros.
  316. EMACS_command::= addresses action.
  317. action::=following
  318. addresses::= empty | address | address, address | whole_file_indicator | global_edit.
  319. global_edit::= g/ pattern /.
  320. address::= simple_address | relative_address | simple_address plus_or_minus number.
  321. relative_address::= + number | - number | + | - .
  322. simple_address::= before_top | last_line | current_line | marked_line | next_line_to_match | previous_line_to_match.
  323. before_top::= 0.
  324. last_line::= $.
  325. current_line::= period.
  326. marked_line::= ' letter.
  327. next_line_to_match::= / pattern /.
  328. previous_line_to_match::= ? pattern ?.
  329. whole_file_indicator::= %
  330. normal_string_delimeter::= /.

    UNIX Edit Actions and Symbols

  331. append::= a lines.
  332. change::= c lines.
  333. delete::= d.
  334. edit::= e force_it_option other_file_symbol | e force_it_option file_name.
  335. other_file_symbol::= #.
  336. insert::= i lines.
  337. move::= m address.
  338. print::= p.
  339. quit::= q.
  340. read::= r source.
  341. source::= file_name | ! unix_command.
  342. substitute::= s / old_string / new_string / flags.
  343. flags::= any of g(global) + c(confirm) + p(print result).
  344. old_string::=pattern | empty.
  345. new_string::=any string of characters but escape special chars like & and /.
  346. write::= w force_it_option append_it_option destination_option.
  347. force_it_option::= empty | ! .
  348. append_it_option::= empty | >>.
  349. destination_option::= empty | file_name.
  350. Symbols::=following
  351. letter::= a..z.
  352. period::= ..
  353. empty::=.
  354. TBA::=To Be Answered.

    Awk -- Ultimate UNIX Tool

    Stream Editting on UNIX

  355. sed::command, edit_every_line_input, edit_every_line_in_files.
  356. edit_every_line_input::= sed sed_options sed_commands
  357. edit_every_line_in files::= sed sed_options sed_commands files
  358. files::=one or more files.
  359. sed_options::= empty | -n, Use -n when no printing is assumed.
  360. sed_commands::= -f filename | sed_command, -- ussually need to put it in quotes!
  361. sed_command::= address action.
  362. action::=print | substitute | delete | add | input | quit | ...
  363. address::= See address">http://cse.csusb.edu/cs360/notes/33.ed+ex.htmladdress.
  364. print::= p
  365. substitute::= s/old/new/ substitute_options
  366. substitute_options::= print_option global_option confirm_option.
  367. print_option::=p.
  368. confirm_option::=c.
  369. delete::=d.
  370. add::= s lines.
  371. input::= i lines.
  372. quit::= q.
  373. lines::= sequence of lines terminated by one that has a period and nothing else on it.
  374. symbolic_sed_commands::=following

    UNIX File slicing and Dicing commands

  375. tr::command, translate_input_characters.
  376. uniq::command, select_unique_lines.
  377. join::command, relational_join
  378. paste::command, paste_files_together_line_by_line.
  379. pr::command, prepare_for_printout.
  380. cut::command, cut_up_input_lines.
  381. translate_input_characters::= tr tr_options input_chars output_chars.
  382. tr_options::= none | - some_of( c | s | d ).
  383. prepare_for_printout::= pr pr_options files.
  384. pr_options::= none | some_of( merge | columns | title | ... )
  385. merge::= -m.
  386. column::= -n.
  387. title::= -t ( none | string ).
  388. cut_up_input_lines::= cut cut_options files.
  389. cut_options::= by_column | by_field.
  390. by_column::= -c some_of( n | n-n | comma )
  391. by_field::= delimiter -f some_of( n | n-n | comma ).
  392. delimiter::= default | -dchar.
  393. default::=none.
  394. paste_files_together_line_by_line::= paste paste_options ( files | dashes).
  395. paste_options::= delimiter | -s.
  396. relational_join::= join join_options files.
  397. select_unique_lines::= uniq uniq_options files.
  398. uniq_options::= count dups_once only_uniq ignore_fields ignore_chars,
  399. count::= -c,
  400. dups_once::= -d,
  401. only_uniq::= -u,
  402. ignore_fields::= - n.
  403. ignore_chars::= + n.
  404. n::=decimal number.
  405. some_of(X)::=take one of each option from list as many timess as you want and concatenate.
  406. string::= a word or title string in quotations.
  407. none::= .

    Sorting data on UNIX

  408. sort::command, see sort_a_file and sort_standard_input.
  409. sort_a_file::= sort sort_options -o filename filename.
  410. sort_standard_input::=sort sort_options.
  411. output_sorted_data_from_files::= sort sort_options filenames.
  412. sort_options::=following
  413. filenames::=one_or_more_of(filename).

    Controling processes in UNIX

  414. nohup::command, dont_kill_this_when_I_log_out
  415. dont_kill_this_when_I_log_out::=nohup command &
  416. signal::=one of 15 or more numbered messages that can be sent from one running process to another on a UNIX machine, See the following list:
    1. STOP::signal=17.
    2. HUP::signal=1, The modem just Hung Up.
    3. INT::signal=2, Interupt
    4. QUIT::signal=3, Stop and dump core.
    5. KILL::signal=9, terminate with extreme prejudice(BSD Manuals:-)
    6. TERM::signal=15, Terminate but gracefully.
    7. STOP::signal=17, stops process until the next CONT or other signal.
    8. CONT::signal=19, continue after a STOP.
    9. TSTP::signal=18, stop and be ready to become foreground or background.
    10. list_all_signals_on_this_system::= kill -l

  417. kill::command. send_signal_to_process, list_all_signals_on_this_system.
  418. send_signal_to_process::= kill -signal process_ids
  419. process_ids::= process_id ...
  420. process_id::=a unique decimal number allocated to every running process on a UNIX system.
  421. ps::command, list_my_processes, list_all_processes
  422. list_my_processes::=ps.
  423. list_users_processes::SYSV= ps -u user_name.
  424. list_users_processes::BSD= ps aux|grep user_name.
  425. list_all_processes::BSD= ps aux.
  426. list_all_processes::=SYSV= ps -elf
  427. trap::command. do_something_when_you_get_any_of_these_signals.
  428. do_something_when_you_get_any_of_these_signals::= trap signals "command".
  429. command::=any UNIX command.
  430. signals::=signal signal ...
  431. ampersand::=&. In UNIX shells an ampresand is put after a command that should be run ind parallel with the net command - typically in the back ground of the users login shell.
  432. SYSV::=AT&T flavored UNIXen.
  433. BSD::=Berkely flavored UNIXen.

    Timing things in UNIX

  434. time::command, time_this,
  435. time_this::= time command arguments_etc.
  436. command::=any UNIX executable
  437. arguments_etc::= list of words and redirections separated by blanks
  438. nice::command, let_the_other_person_go_first.
  439. let_the_other_person_go_first::= nice command arguments_etc.
  440. uptime::command. outputs stats about loads etc...
  441. w::command, outputs uptime and then lists what people are doing.
  442. list_load_and_what_people_are_doing::= w.

    Sleeping and waiting in UNIX

  443. sleep::command, wait_roughly_this_number_of_seconds.
  444. wait_roughly_this_number_of_seconds::= sleep n.
  445. n::=any whole decimal number.

    Setting up a terminal for old fashioned UNIX

  446. stty::command, check_terminal_settings, read_the_stty_manual, [ 05.terminals.html ]
  447. man::command, to brouse thought the online manuals.
  448. check_terminal_settings::= stty | stty -a | stty -everything.
  449. read_the_stty_manual::=man stty.
  450. tty::=teletype, an ancient but cheap terminal used on the First World Wide electronic network: Telex.
  451. ptty::=Pseudo-tty used on Xwindows.

    People and UNIX

  452. Understand the problem area:
  453. Get Tools:
  454. Understand the particular problem in front of you.
  455. Act:
  456. Check:
  457. Learn:

  458. SNAFU::= Situation Normal: All Fouled Up. A phrase invented by the US
  459. FUBAR::= Fouled Up Beyond All Recognition.
  460. Fouled::=the GIs used a word in place of Fouled with a similar meaning but a stronger emphasis...

    Formating data on UNIX

  461. pr::command, prepare_to_print.
  462. banner::command, make_a_banner.
  463. make_a_banner::= banner words.
  464. prepare_to_print::= pr pr-options files
  465. pr_options::= pr_number_of_cols | pr_no_title | pr_header | pr_merge_files |...
  466. pr_number_of_cols::= -n.
  467. pr_no_title::= -t.
  468. pr_header::= -h string.
  469. pr_merge_files::= -m.
  470. display_files_with_headers::= head -10000 files
  471. n::=any whole number in decimal.
  472. string::=any string - but put it in quotes.
  473. words::= some words inside quotes.
  474. width::=a decimal number between 10 and 250.

    br - Break Lines Up (CSUSB only)

  475. br::a_local_command, break_long_lines.
  476. break_long_lines::= br width.

    THis is a program I wrote and installed on most of the UNIXen that I administered -- or just compiled into my local ~/bin directory... Very useful and guarantee'd correct

    Shell commands

     		br
    		br <infile >outfile

    Used inside vi.

     		!!br			word wrap this line
     		!Gbr			word wrap rest of file
     		1G!Gbr 40		word wrap whole file to 40 characters
    		~|br
    [ br.l ] (manual) [ br.l.cat ] (printable manual) [ br.c ] [ brt.c ] (Source code -- K&R C) [ br.c ] (ANSI C) [ br.d.html ] (documentation).

    Writing Scripts for UNIX

     		chmod a+rx name_of_file
     		: comment
    		command arg1 arg2 arg3 ...
    		$0 is command
    		$1 is arg1
    		$2 is arg2
    		...
     	case $# in
     	0) echo Usage: $0 ..... ; exit 1;;
     	1) file=$1; do_something_to_file
     	;;
     	*) for file; do $0 $file; done ;;
    [ unix.syntax.html ]
  477. command_line_argument::= $n.
  478. remove_first_argument_etc::= shift.
  479. number_of_command_line_arguments::= $#.
  480. exit_status_of_last_command::= $?.
  481. all_arguments::= $*.
  482. all_arguments_in_quotes::="$@".
  483. this_process_s_id::=$$.
  484. test_for_some_condition::= test_command | [ test_options ] | test_string_for_a_pattern.
  485. test_string_for_a_pattern::= See http://cse.csusb.edu/cs360/notes/45.scripts.html#test_string_for_a_pattern.
  486. test_command::= test test_options.
  487. test_exprression::=test_options.
  488. test_options::= test_option | test_option space test_boolean_operator space test_options | not space test_option.
  489. not::= !.
  490. space::=mandatory spaces or tab characters.
  491. test_option::= value space -fortran_comparison space value | -file_state file | string string_comparison string.
  492. file_state::= r | s | z | d | ...
     	if test -r .profile; then echo .profile exists.; fi

    1. r::file_state=readable.
    2. d::file_state=directory.
    3. s::file_state=readable and nonempty.
    4. z::file_state=readable and empty.
    5. ...(depending on your system)
       		man test

  493. file::=possible name of a file -- string of letters and digits variable ....
  494. value::= any_valid_shell_argument.
  495. fortran_comparison::= lt | le | eq | ne | gt | ge.
     	if test $# -eq 3; then echo Command has three arguments; fi

    1. lt::fortran_comparison=less than,
    2. ge::fortran_comparison=greater than or equal,
    3. ne::fortran_comparison=not equal to,
    4. eq::fortran_comparison=is equal to,
    5. le::fortran_comparison=is lessthan or equal to,
    6. ge::fortran_comparison=is lessthan or equal to.

  496. string_comparison::=test_strings_equal | test_strings_not_equal.
  497. test_strings_egual::= =.
  498. test_strings_unequal::= !=.
  499. string::=xany sequence of words and arguments and variable values in quotes.
  500. test_boolean_operator::= test_and | test_or.
  501. test_and::= -a.
  502. test_or::= -o.
  503. output_result_of_expression::= expr expression.
  504. put_output_of_expresion_in_command::= reverse_quote expr expression reverse_quote.
  505. test_string_for_a_pattern::= expr expression : expr_pattern >/dev/null,
     		if expr $1 : "-" ; then # first argument starts with a dash.
  506. reverse_quote::="`".
  507. expr_command::=exor expression.
  508. expression::= element | expression expr_operator expression ... .
  509. expr_operator::= + | - | \* | / | % | = | != | > | >= | < | <= | vertical_bar | ampersand | colon_operator.
  510. colon_operator::expr_operator. Matches its first string argument against a expr_pattern in the second argument.
  511. expr_pattern::=a pattern with wild cards for characters + repetition with * and the ability to select a part of the pattern "\(....\)". Warning the pattern is always anchored at the start of the string. [ 26.patterns.html ]
  512. element::= string | constant | \( expression \).
  513. ampersand::= "&".
  514. vertical_bar::= "|".
  515. string::=any string in double or single quotes with usual shell rules, of
  516. constant::=number | word.
  517. number::= sequence of decimal digits.
  518. word::=sequence of words and values of variables with no whitespace...

    How to Appear Organized using UNIX: Calendars

     		In vi Command mode	:!cal
     		In vi Input mode	<Esc>:!cal
     		Input it into text while
     		  in vi command mode
     		  on a blank line	!!cal
    		In ex			!cal
    		Sending mail with mailx	~!cal
    		Reading mail with mailx	!cal
    		On the WWW with Lynx	!cal		(and then CTRL/D)

    Using UNIX commands inside other programs

  519. vi_command_shell_escape::= :! shell_command.
  520. ex_command_shell_escape::= ! shell_command.
  521. mailx_command_shell_escape::= ! shell_command.
  522. lynx_command_shell_escape::= ! shell_command.
  523. sending_mailx_shell_escape::= ~! shell_command.
  524. vi_command_shell_escape::= :! shell_command.
  525. daemon::=a program that runs without a user invoking it at a terminal.

    UNIX Script expressions

    TBA

    Miscelaneous UNIX Commands

    [ jargon.html ]
  526. who::command, lists users, RTFM
  527. script::command, records what happens in a file.
  528. RTFM::=Read the Famous Manual... See man

End