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Text File | 1993-12-31 | 16.8 KB | 511 lines

Monday 21-Sep-92 15:20:38 AXSH(1) USER COMMANDS Version 1.26 NAME AXsh - a shell (command interpreter) SYNOPSIS AXsh DESCRIPTION AXsh, the AXshell, is a command interpreter with a number of convenient features for interactive use that are or are not available with the standard AmigaDOS shell, including command aliasing,history events, variables, filename and command name completion , shell level protections and a number of built-in commands. OPTIONS -con Turn off carrier checking (console mode) and allow superusers to run any program they like, even those NOT in the /etc/rc file (they have to be in the path though). -log Keep log (AXsh:etc/adm/log.*) -user <user> Accepts user without asking the password. Account for the user must still exist in /etc/passwd. In this mode "login" command causes relogin with the same login name. This option is useful with closed UUCP systems, where getty is answering the calls and you don't want to have two login-prompts. -nullmodem Indicates that there will be no Carrier present and AXsh should ignore any carrier loss. Command Line Editing The command line editor has two modes depending on the 'term' environmental variable (vt100 or ANSI). In ANSI-mode it sends more bytes, so vt100-mode is recommended. Just make sure that your emulation matches the setting. It seems that most vt100- terminals really don't like to work with the ansi-mode. The editor knows about these commands: left/right ^B/^F Moves cursor left and right up/down ^P/^N Recalls history events Shift-left ^A Goto the start of line Shift-right ^E Goto the end of line Shift-up, Shift-TAB History completion Backspace Delete previous character Delete Delete current (next) character ^D Like Delete or display matching files if cursor is in the EOL ^L, ^R Refresh line ^K Delete to the end of line ^U Delete to the start of line ^W Delete previous word ^X Delete line ^Y Yank killed text back TAB (^I) Try command/filename completion Return/Newline (^J/^M) End editing :-) HELP String assigned in variable HELP F1 String in variable F1 : : : : F20 String in variable F20 Command Line Parsing A simple command is composed of a sequence of words. The first word specifies the command to be executed. One line can have several commands separated with a semicolon (";"). Variable substitution In case '$' is encountered, it is treated as an environmental variable and the variable is replaced by its value. If the variable is to be part of a word, it must be surrounded by braces of some kind. The substitution is not done inside the quotes. List of the reserved and special variables may be found elsewhere in this document. $name Normal type, will (usually) select the whole variable as is. $name[select] Selects only one word from the variable. Numbering starts from zero. If the referenced word doesn't exist,a NULL string is returned. ${name}[select] When the variable name contains spaces or '[' chars , it must be surrounded by braces. Any pair of "()", "[]" and "{}" are considered as braces. examples: > echo $user root > echo ${tty}/$[host] $(quota)kB con7/amiga.pasbox.fi 30kB > echo ${s p a c e} You can still use $-sign by doubling it ($$->$). Another way to use $-sign is to preceed it with a back-slash (\). There is a special variable: $< , which reads a line from the standard input and that line is appended to the command line as is. No future parsing is done to the string read. Each variable is inserted as a single argument, even if it consists of several words. If you want to add something to the same argument, you can use e.g. $[var1]" text "$var2 "a"\"$[var]\""b" Command Separator If you want to execute several commands from a single line you can use ';' as a delimiter. This command separator works only with command line, not from scripts. In script files semicolon is used as a comment-mark! e.g. "cd arc: ; ls" If you want to use semicolon on its own, preceed it with a backslash: "\;". The same applies to every special character. e.g. "echo ls \; more file\ name ; ls ; more file\ name" History Events History events allows you to call for already typed lines for editing. You can use either cursor keys up/down or type the !-character and the command number. History numbers can be found out with the 'history'-command,which is built in the getline-routine. The number of history-lines is fixed and cannot be set by user. History completion may also be used. Write the start of the command line and press shift-TAB. The history completion works almost like filename completion. Command, history, directory and filename completion The command line editor offers you the ability to complete a partial filename by pressing TAB (^I). If the name matches several files or directories, expansion is made only to the extent it can be made and a BELL (^G) is printed. You can also display all matching filenames by pressing ^D. However, the cursor should be in the end of the line. If you apply TAB (^I) to the first word on a line,the word is treated as a command and the completion is made accordingly. If no perfect match was found on the command set, a filename completion is tried. Remember that these actions are separate and a partial completion may be performed in the ccomp routine before passing the partial filename to fcomp. You can do completions on redirections too. History completions are also possible. This function can be invoked using shift+cursor_up or shift-TAB. It behaves like fcomp and beeps for a partial completion. Aliases The AX shell maintains a list of aliases that you can create, display and modify using the alias and unalias commands. The shell checks the beginning of each command line to see if it matches a name of an existing alias. If it does, the command is reprocessed with the alias definition replacing its name. Aliases shouldn't be nested . An alias definition shouldn't contain another alias as the first command, because the alias substitution is made only once for each command. So,recursive aliases are not possible , but looping aliases are easy to create. To break such loop, you may have to send successive BREAKs (^C) for undefined period of time (depending on the command inside the loop). (ex. alias loop wait 10\;loop) You cannot make an alias for strings 'alias' or 'unalias', so these commands are always accessible. Aliases are case-sensitive, so you can escape an alias by typing the command using a different case. I/O Redirection The following metachars indicate that the subsequent word is the name of a file to which the command's standard output is redirected. Standard input cannot yet be redirected. Redirection does not work with all of the shell builtins. > Redirect the standard output to a file . If the file does not exist, it is created. If it does exist,it is overwritten; its previous contents are lost. >> Append the standard output. Like >, but places output at the end of the file rather than overwriting it. If the file does not to exist, it is created. | Simple piping. Everything after the pipe symbol in the command line is considered to be another command. The piping uses temporary files created in T:. Redirection and piping can't be used simultaneously ! Command Execution If the command is a AXshell built-in, the shell executes it directly. Otherwise, the shell searches for a file by that name with execute permission. If the command-name contains a / or a : the shell takes it as a pathname, but completely ignores it. This way unsecure commands won't be executed. You can also use this feature to supress alias-replacement. e.g. c:dir would use the command 'dir', not the alias for dir For superusers in local (console) mode things are not as simple. Paths are used as is and the shell path is also searched. Signal Handling The AXshell normally ignores all signals. Ctrl-D is checked only if the ignoreeof-variable it SET. Ctrl-C it not yet used for anything. It is upto the running program to acknowledge break signals. AXsh will exit if it detects an EOF situation or a loss of carrier. If you open AXsh in a window with a close-gadget, it can also be used to make AXsh exit. Directory and filename expansion The shell expands all arguments containing ':' or '/' chars. This way all external commands get the right parameters and you still have a consistent referencing in filesystem: you can use '~/' to refer to home dir with any command. This expansion can be turned off by defining the 'f'-flag for the command in AXsh:etc/rc. This means that the argument is not a filename. Wildcard expansion isn't made by AXsh,but the command itself, if it supports wildcards. This may change in the future. Built-In Commands Built-in commands are executed within the AXshell. ; Null command.This command is interpreted,but performs no action. Actually this contains two null-commands. In script files semicolon is used as a comment mark. alias [ name [ def ] ] Assign "def" to the alias name. "name" is not allowed to be "alias" or "unalias" . If def is omitted , the alias name is displayed along with its current definition. If both the name and def are omitted, all aliases are displayed. The name is the first argument and the definition is the second. e.g. alias help "man axsh" You can remove all aliases with "alias clear". cd [ dir ] Change the shell's working directory to directory dir. If no argument is given, change to the home directory of the user. ~ denotes home directory and : denotes the root directory of the current working directory. '..' is the parent directory and / is the AXsh: assign or disk. "cd" may be omitted , if there is no command mathing the directory name. echo Just prints out everything to the output. Mainly used on script files for output. The trailing newline is not printed if the first argument is "-n" or the last argument is "noline". Example: echo $realname has logged on $host execute script-file Get the commands from a specified file. The execution continues until the end of file is reached or if an error occurs. Empty lines are skipped. Scripts can be nested, but the recursion depth is limited. Since 1.3 you can also redirect the output of a script. "execute" may be omitted, if there is no command with the same name as the script-file nor a directory with the same name (currently this is impossible in Amiga). "execute" still appears as the zeroth argument to the script. The script file bit must also be set if you plan to start the script with only its name ! exit The shell exits and hangs up, if remote connection. ftp file [file2 ..] Will copy the file(s) to the home directory. internal Lists all internal commands. It is still possible that they aren't allowed to all users, depending on /etc/rc. login Terminate a login and initiate a new one. protect modes file [file2 ..] Parses the mode argument and then sets the protection bits accordingly. You can set, clear and toggle ANY defined bit, including group and world protection bits. e.g. protect go+r-w /etc/systemaliases However, THESE BITS ARE NOT USED in AXsh yet, but ls shows them. quit A null-command. Otherwise used to exit scripts. quota Shows home filesystem , number of files used , disk space used and usage limit. Will return warning level (5) if the quota is exceeded. set [ var [ definition ] ] Create or modify a shell variable. There are several predefined ones that cannot be changed and some, with whom the changes are discarded. Actually all variables are currently environmental variables, but this is supposed to change. The variable name is the first argument and the definition is the second. From version 1.3 all AXsh variables are exported to 2.0 shell local variables. You also have a list of WORM- variables that can only be set once (/etc/ForbiddenVars). e.g. set HELP "cat /etc/motd\n" -- System variables: user user's login name tty which terminal 'line' the user uses accesslevel just what it says. realname full name of the user home user's home directory host current host name dosv system version intime time the user has been logged in (mins) -- Special variables: autologout in minutes - time between keystrokes in AXsh for automatic logout. language What catalog to use. If the language is not found or the variable is not set, English is used. Currently you can select one of these: suomi (Finnish) français (French) dansk (Danish) español (Spanish) svenska (Swedish) Or use the default English. cwd current working directory quota disk space currently used (in kB) lasterr return code from the last command ioerr IoErr() returned by the last external command Lasterr and ioerr are not seen in the variable list. term terminal emulation (vt100 or ansi, def:ansi) rows number of rows on terminal (default: 24) visual name of the full screen editor (def: editor) edscroll scroll length in lines (in editor) prompt the prompt format: Variables: %% % itself %d current working directory %h command counter %l line (terminal) %M hostname %q actual quota/limit %r full name %t time (full time now, might change) %u username %i intime (in minutes) C-style special codes: \e ESC \t TAB \n Newline \r CR \a BEL Control codes: ^L Ctrl-l ^G Ctrl-g etc.. any other character as is, default prompt is "%h.%d> " Example: set prompt "\\e[1m(%u)\\e[m %%%h \\e[7m%d\\e[m > " Notice that you have to double the backslashes, because they have precedence over doublequotes. ignoreeof if this variable is set, ^D will do exit.. It is actually reversed from the tcsh. HELP You can create macros by defining these F1 variables. e.g. .. set F1 "^a^d^d^d^drm^e" F20 will goto start of line, delete 4 chars, add "rm" and goto end of line when you press F1. C-style codes and control characters are like in the prompt. -- Special variables in scripts -- argument Works only with a word specifier, not as $argument. argument[0] is 'execute', argument[1] is the script name (possibly including path) etc. This variable is not seen in the variable list. sysinfo Print out some information about the OS version etc. unalias word [word2 .. [wordn]] Discard one or more aliases. unset var [var2 .. [varn] ] Discard one or more shell variables. upload file [file2 ..] Copies the file(s) to the system upload directory. uptime Displays uptime and system load information. wait time Goto sleep for time (in seconds). Wait can be stopped with a keypress. which command Will show from where the command is executed. e.g. %14 (root) AXsh:home/root/ 169 > which dir AXsh ALIAS DH0:Oldsys/C/Dir c:dir Dir is an alias, but otherwise DH0:oldsys/c/dir would have been executed. There is also another dir in the command search path, c:dir. who Displays uptime and load information with a list of the users currently logged in. whoami Print out your current login name write user text [text ..] Will send the text to another user in the system. If the user is not logged in, an error message is displayed instead. Special script file commands The if-construct is a bit lame, but there simply are some more important features to think about.. if Keywords for if-else-endif -contruct. else The condition can be one of the forms : endif "foo" == "foo" "bar" != "foobar" exists file If you use variable, the form depends on the variable $var != "foo" will become: "" != "foo" , if the variable is empty and var != "foo" , if the variable is unset goto label Jumps to a defined label. It is an error if the label doesn't exist. quit Exits the script label: [command] Command labeling . The command is optional, and the label is ignored in the command execution. A label name cannot have spaces in it. ; comment Commenting. Starts a comment which proceeds to the next end-of-line. FILES /bin/AXsh AXsh executable /etc/rc Configuration file /etc/ForbiddenVars File holding all untouchable variables: <varname> [<number of sets allowed>] /etc/GlobalLogin Script executed at login, can be used to set system variables like POSTNEWS etc. Still executed with user's privileges. ~/.lastlogin Showed by the login shell at login. ~/.logout Script which is EXECUTEd at logout ~/.login Script which is EXECUTEd at login SEE ALSO login, exit, cd, execute