page@swan.ulowell.edu (Bob Page) (10/25/88)
Submitted-by: dillon@cory.berkeley.edu (Matt Dillon)
Posting-number: Volume 2, Issue 21
Archive-name: unix/shell211.doc
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SHELL V2.11 (C)Copyright 1986-88, Matthew Dillon, All Rights Reserved.
Freely distributable for non-profit only.
old users: Please read the version history at the bottom of
this document for changes and additions.
(A) Compiling
(B) Overview
(C) Quicky tech notes on implimentation.
(D) Command pre-processor
(E) Command-list
(F) special SET variables
(G) Version history
See also EXAMPLES.TXT
NEW FEATURES THIS VER
(Taken from the history below): an IPC implementation, ENV: variable
support, many commands enhanced, some bugs fixed.
COMPILATION
The SHELL will compile only under AZTEC C and requires my
support library (SUP32.LIB) to link as well as a precompiled
symbol table of all AMIGA .H files. A Makefile is included.
Note that the shell must be compiled using 32 bit integers (+L)
option and linked with SUP32.LIB and C32.LIB. Additionaly, my
dres.library must be present in order to use the IPC facility.
NOTE that converting the shell to use 16 bit integers does not
make it significantly smaller or faster. Do not waste your time.
OVERVIEW
Matthew Dillon
891 Regal Rd.
Berkeley, California 94708
USA
..!ucbvax!dillon
dillon@ucbvax.Berkeley.EDU
dillon@cory.Berkeley.EDU
This is not a shareware program. My basic philosophy is to write
software for myself and distribute it if I think it will benefit
others (that is, unless I start going broke). Contribute if you want
to.
IT IS SUGGESTED THAT YOU USE CONMAN OR THE NEW 1.3 ENHANCED CONSOLE
DEVICE. CONMAN does to my shell what Steve did in his Manxfied (old
term) 16 bit version of my shell, and more. It isn't required, but
CONMAN (shareware) complements the functionality of the shell quite
well.
PROBLEMS
-Make sure you give the SHELL a big enough stack, especially if you
intend on running shell scripts which source other scripts. 8192
is suggested. Remember, STACK must be run BEFORE you run the shell.
Running it from the shell does not effect the shell's stack.
-You should not redirect the RUN command. to redirect the command the
RUN command is running, embed a standard CLI redirection in the command
string:
RUN ">file" command
-Append '>>' does NOT work with BCPL programs. It does work with all
internal and non-bcpl (read C) programs.
OVERVIEW of the major features:
-History mechanism (complements conman quite nicely, in fact)
-Redirection
-Piping (sort of)
-Command search path by name and by CLI path list
-Aliases
-Variables & variable handling (embedded variables), and enviroment variables
-Automatic file name expansion via '?' and '*'
-Conditionals
-Shell Scripts
-many built in commands to speed things up
COMMAND PREPROCESSOR
preprocessing is done on the command line before it is passed on to
an internal or external routine:
^c where c is a character is converted to that control character.
Thus, say '^l' for control-l.
$name where name is a variable name. Variable names can consist of
0-9, a-z, A-Z, and underscore (_). The contents of the
specified variable is used. If the variable doesn't exist,
the specifier is used. That is, if the variable 'i' contains
'charlie', then '$i' -> 'charlie'. If the variable 'i' doesn't
exist, then '$i'->'$i' .
; delimits commands. echo charlie ; echo ben.
' ' (a space). Spaces delimit arguments.
"string" a quoted string. For instance, if you want to echo five spaces
and an 'a':
echo a -> a
echo " a" -> a
\c overide the meaning of special characters. '\^a' is a
circumflex and an a rather than control-a. To get a backslash,
you must say '\\'.
also used to overide alias searching for commands.
>file specify output redirection. All output from the command is
placed in the specified file.
>>file specify append redirection (Does not work with BCPL programs).
<file specify input redirection. The command takes input from the
file rather than the keyboard (note: not all commands require
input). It makes no sense to say 'echo <charlie' since
the 'echo' command only outputs its arguments.
| PIPE specifier. The output from the command on the left becomes
the input to the command on the right. The current SHELL
implimentation uses temporary files to store the data.
!! execute the previously executed command.
!nn (nn is a number). Insert the history command numbered n (see
the HISTORY command)
!partial search backwards through the history list for a command which
looks the same as 'partial', and execute it.
# Enter comment. The rest of the line is discarded (note: \#
will, of course, overide the comment character's special
meaning)
^search^replace
a '^' at the beginning of the line indicates history
replacement. The first occurance of 'search' in the previous
command is changed to 'replace', and the command executed.
SHELL COMMANDS
The first argument is the command-name... if it doesn't exist in the
list below and isn't an alias, it is assumed to be an external (disk)
command.
AUTOMATIC SOURCING may be accomplished by naming shell scripts with a
.sh suffix. Thus, if you say 'stuff' and the file 'stuff.sh' exists in
your current or C: directory, it will be SOURCED with any arguments you
have placed in the $_passed variable.
EXCEPTION_PROCESSING
if no _except variable exists, any command which fails causes the
rest of the line to abort as if an ABORTLINE had been executed. If
the _except variable exists, it is of the form:
"nnn;commands..."
where nnn is some value representing the minimum return code required
to cause an error. Whenever a command returns a code which is
larger or equal to nnn, the commands in _except are executed before
anything. WHEN _except EXISTS, THE COMMAND LINE DOES NOT ABORT
AUTOMATICALLY. Thus, if you want the current line being executed
to be aborted, the last command in _except should be an "abortline".
exception handling is disabled while in the exception handling routine
(thus you can't get into any infinite loops this way).
Thus if _except = ";", return codes are completely ignored.
example:
set _except "20;abortline"
ABORTLINE
or just 'abort'. Causes the rest of the line to be aborted. Used in
conjunction with exception handling.
% echo a;abort;echo b
a
HELP
simply displays all the available commands. The commands are
displayed in search-order. That is, if you give a partial name
the first command that matches that name in this list is the one
executed. Generally, you should specify enough of a command so that
it is completely unique.
QUIT
EXIT
RETURN [n]
quit my SHELL (awww!). End, El-Zappo, Kapow. Done, Finis. If you
use RETURN and are on the top source level, the shell exits with the
optional return code. (see RETURN below)
SET
SET name
SET name string
The first method lists all current variable settings.
The second method lists the setting for that particular variable,
or creates the variable if it doesn't exist (to "")
The last method sets a variable to a string.
see the section on special _ variables down below
UNSET name name name....
unset one or more variables. Deletes them entirely.
SETENV name string
Create/Modify an enviroment variable. The enviroment is maintained
in ENV:, with a separate file for each enviroment variable. This
should be assigned to a directory somewhere.
UNSETENV name name name....
remove the specified variables from the enviroment list. This
call DeleteFile()'s the enviroment variable from ENV:
PRINTENV
Print the contents of the enviroment directory ENV:
ALIAS
ALIAS name
ALIAS name string
same as SET, but applies to the alias list. You can alias a single
name to a set of commands. For instance:
alias hi "echo a; echo b"
then you can simply say 'hi'. Aliases come in two forms the second
form allows you to place the arguments after an alias in a variable
for retrieval:
alias xxx "%i echo this $i is a test"
% xxx charlie
this charlie is a test
The rest of the command line is placed in the specified variable
for the duration of the alias. This is especially useful when used
in conjunction with the 'FOREACH' command.
UNALIAS name name name...
delete aliases..
ECHO string
ECHO -n string
echo the string to the screen. If '-n' is specified, no newline is
output.
STRHEAD varname breakchar string
remove everything after and including the breakchar in 'string' and
place in variable 'varname':
% strhead j . aaa.bbb
% echo $j
aaa
%
STRTAIL varname breakchar string
remove everything before and including the breakchar in 'string' and
place in variable 'varname':
% strtail j . aaa.bbb
% echo $j
bbb
%
SOURCE file [arguments]
execute commands from a file. You can create SHELL programs in
a file and then execute them with this command. Source'd files
have the added advantage that you can have loops in your command
files (see GOTO and LABEL). You can pass SOURCE files arguments
by specifying arguments after the file name. Arguments are passed
via the _passed variable (as a single string).
Automatic 'sourcing' is accomplished by placing a .sh extension on
the file and executing it as you would a C program:
--------- file hello.sh ---------
foreach i ( $_passed ) "echo yo $i"
---------------------------------
% hello a b c
yo a
yo b
yo c
NOTE: The hash '#' as the FIRST character on the line is a comment
within script files.
MV from to
MV from from from ... from todir
Allows you to rename a file or move it around within a disk. Allows
you to move 1 or more files into a single directory. (if todir == '/',
the items are moved to the parent directory).
CD
CD ..
CD path
Change your current working directory. You may specify '..' to go
back one directory (this is a CD specific feature, and does not
work with normal path specifications). Note that CD / also goes
back one directory.
CD without any arguments displays the path of the directory you
are currently in.
PWD
rebuild _cwd by backtracing from your current directory. The $_cwd
variable can get confused by Assign'd labels.
RM [-r] file file file...
DeleteFile(). Remove the specified files. Remove always returns
errorcode 0. You can remove empty directories. The '-r' option
will remove non-empty directories by recursively removing all sub
directories.
CP file (to current directory)
CP [-r] dir (to current directory)
CP file file
CP file1 file2...fileN dir
CP [-r] dir1 dir2...dirN dir
copy files or directories. when copying directories, the "-r" option
must be specified to copy subdirectories as well. Otherwise, only
top level files in the source directory are copied.
MKDIR name name name...
create the following directories.
HISTORY [partial_string]
Displays the enumerated history list. The size of the list is
controlled by the _history variable. If you specify a partial-
string, only those entries matching that string are displayed.
MEM
Display current memory statistics for CHIP and FAST memory.
CAT [file file....]
Type the specified files onto the screen. If no file is specified,
STDIN in used. CAT is meant to output text files only. You cannot
use CAT to join binaries together.
DIR [-s] [path path ... ]
Get a directory listing of the current directory or specified
directories. The -s option causes DIR to display a short-form
listing.
DEVINFO [device: device:... ]
Display Device statistics for the current device (CD base), or
specified devices.
FOREACH varname ( strings ) command
'strings' is broken up into arguments. Each argument is placed in
the variable 'varname' in turn and 'command' executed. To execute
multiple commands, place them in quotes:
% foreach i ( a b c d ) "echo -n $i;echo \" ha\""
a ha
b ha
c ha
d ha
Foreach is especially useful when interpreting passed arguments in
an alias or source file.
NOTE: a GOTO inside a FOREACH will have an indeterminate effect.
FOREVER command
FOREVER "command;command;command..."
The specified commands are executed over and over again forever.
-Execution stops if you hit ^C
-If the commands return with an error code.
NOTE: a GOTO inside will have an indeterminate effect.
RETURN [value]
return from a source file. The rest of the source file is
discarded. If given, the value becomes the return value for the
SOURCE command. If you are on the top level, this value is returned
as the exit code for the shell.
IF -f path
IF argument conditional argument ;
IF argument
If a single argument is something to another argument. Conditional
clauses allowed:
<, >, =, and combinations (wire or). Thus <> is not-equal, >=
larger or equal, etc...
If the left argument is numeric, both arguments are treated as
numeric.
usually the argument is either a constant or a variable ($varname).
The third form if IF is conditional on the existance of the argument.
If the argument is a "" string, then FALSE , else TRUE.
The first form is TRUE if the path can be openned with modes 1005.
ELSE ;
else clause.
ENDIF ;
the end of an if statement.
LABEL name
create a program label right here. You can only have labels within
a source file.
GOTO label
goto the specified label name. You can only use this command from a
source file.
DEC var
INC var
decrement or increment the numerical equivalent of the variable and
place the ascii-string result back into that variable.
INPUT varname
input from STDIN (or a redirection, or a pipe) to a variable. The
next input line is placed in the variable.
VER
display my name, the version number, and the version date.
IPC appname[.project] command
Send an IPC command to the .CMD IPC domain for the specified
application. An optional project name within that application
may be supplied. The text command is sent to the application.
Only applications that support the DRES.LIBRARY IPC interface
can communicate via this command. DRES.LIBRARY must exist for
this command to work. Examples:
forever "ipc dmouse mouse;ipc dmouse nomouse" (DMouse V1.11 and beyond)
Currently, the shell cannot receive IPC commands.
SLEEP timeout
Sleep for 'timeout' seconds.
SPECIAL VARIABLES
_prompt
This variable is set to the command you wish executed that will
create your prompt.
_history
This variable is set to a numerical value, and specifies how far
back your history should extend.
_histnum
This variable contains the history # of the next command that
will be executed.
_debug
Debug mode... use it if you dare. must be set to some value
_verbose
Verbose mode (for source files). display commands as they are
executed.
_maxerr
The worst (highest) return value to date. To use this, you usually
set it to '0', then do some set of commands, then check it.
_lasterr
Return code of last command executed. This includes internal
commands as well as external comands, so to use this variables
you must check it IMMEDIATELY after the command in question.
_cwd
Holds a string representing the current directory we are in from
root. The SHELL can get confused as to its current directory if
some external program changes the directory. Use PWD to rebuild
the _cwd variable in these cases.
_passed
This variable contains the passed arguments when you SOURCE a file
or execute a .sh file. For instance:
test a b c d
-------- file test.sh ----------
echo $_passed
foreach i ( $_passed ) "echo YO $i"
--------------------------------
_path
This variable contains the search path when the shell is looking
for external commands. The format is: DIR,DIR,DIR Each DIR must
have a trailing ':' or '/'. The current directory is always
searched first. The entire path will be searched first for the
<command>, then for <command>.sh (automatic shell script sourcing).
The default _path is set to "c:,ram:,ram:c/,df1:c/,df0:c/"
NOTE: The CLI path is also searched.
_ignoreeof
If this variable exists, EOF is ignored on interactive
terminals. This prevents accidental logouts.
_copysilent
If this variable exists, the CP command will be silent. The
default is now for CP to be verbose.
_copydate
If this variables exists, the CP command will attempt to
transfer the datestamp src->dst file/dir. For directories,
only those that CP must create will get the old datestamp
transfered to them. Additionaly, the COMMENT, if any, will
the transfered src->dst file/dir.
TECH NOTES
PIPES have been implimented using temporary RAM: files. Thus, you
should be careful when specifying a 'ram:*' expansion as it might
include the temp. files. These files are deleted on completion of
the pipe segment.
The file names used are completely unique, even with multiple shells
running simultaniously.
My favorite new feature is the fact that you can now redirect to and
from, and pipe internal commands. 'echo charlie >ram:x', for
instance. Another favorite:
echo "echo mem | shell" | shell
To accomplish these new features, I completely re-wrote the command
parser in execom.c
The BCPL 'RUN' command should not be redirected.. .strange things
happen. You can use redirection WITHIN the RUN's command line, of
course, but it should be quoted so the shell doesn't think the
redirection is for it.
NO BCPL program should be output-append redirected (>>).
VERSION HISTORY
V2.11:
-IPC command added (requires dres.library to work). All new
versions of my programs will support this IPC interface.
V2.10:
-Command dispatch has been fixed... RUN used to create problems
sometimes (would give you a CLI prompt when it should not have).
-MV fixed ... had problems when moving things to the current
directory ("") and names starting with '/'.
-SETENV, PRINTENV commands added. $var variables search the
enviroment (ENV:). Aliases are searched for in ENV: as well
now.
This allows you to have global variables and aliases for all
the shells running in the system without having to re-source an
initialization file. Additionaly, to the limits of the command
line, the contents of any file in ENV: may be inserted by
referencing it as a variable.
ANY system variable may be placed in the enviroment instead of
the local variables if you wish.
-DIR enhanced. Defaults to long list format.
V2.08:
-WaitForChar() removed from main processing loop (the old Delay(0)
bug though in this case it is WaitForChar(x,1).
-CP now accepts single parameters (ala MSDOS).. copy a file or
directory to the current directory (-r for recursive sub-dirs)
CP FILE
CP [-r] DIR
-A new variable, _copydate, which, if it exits, causes CP to
transfer both the comment and datestamp of the source to the
destination.
set _copydate
V2.07: (Internal)
V2.06B:
-External programs that change the current directory are caught,
and no longer crash the machine.
-CP command, the _copysilent variable, if it exists, causes
directory and recursive copies to do their work in silence.
V2.06:
-IF enhanced. -f option added. (if -f path). If the named path
can be openned with modes 1005, then...
-various routines fixed.
V2.04:
- CP command now internal... see instructions.
- RM command now has '-r' option.
- \command forces the command parser NOT to look at aliases. Thus,
you can alias something like 'cd' and have the alias contain a 'cd'
which references the internal cd:
alias cd "stuff...;\\cd $x"
- "-c" command line option to execute commands and return.
shell -c "echo a;echo b;echo c".
- _path default now places RAM: and RAM:C first rather than last.
- _histnum variable .. current history #
- expanded filenames are sorted.
- ^search^replace (modify previous command).
V2.03 AND BELOW
Before Written History (actually not quite, but there was this
fire you see....)
\Rogue\Monster\
else
echo "will not over write shell.doc"
fi
if [ `wc -c shell.doc | awk '{printf $1}'` -ne 21457 ]
then
echo `wc -c shell.doc | awk '{print "Got " $1 ", Expected " 21457}'`
fi
echo "Finished archive 1 of 1"
# if you want to concatenate archives, remove anything after this line
exit
--
Bob Page, U of Lowell CS Dept. page@swan.ulowell.edu ulowell!page
Have five nice days.