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Addendum for Version 1.4 SKsh A ksh-like Shell for the Amiga Version 1.7 (Copyright) 1988-1991 Steve Koren May 4, 1991 Addendum to Version 1.4 This document describes additions and changes to SKsh since version 1.3. Beta version of tiny_sksh SKsh 1.4 includes a preliminary version of tiny_SKsh, an SKsh without command line editing, history, or a number of builtin commands. It does, however, include the entire SKsh command parser with all control structures, tests, pipes, command substitution, shell functions, aliases, etc. This shell is still a "beta" version - most of the SKsh builtin commands are not yet provided as external commands for tiny_SKsh. It is possible, however, to test whether a given script is being run under full or tiny SKsh. tiny_SKsh is described in more detail in the TinySKsh.doc file. SIZE variable added A new SIZE variable has been added which contains either "normal" or "tiny". It can be used to test for a specific version of SKsh. case...esac statement added The case...esac construct now works in SKsh. It is mostly compatible with the ksh or sh case statement. For example, read answer case "$answer" in abc) echo 'You typed abc' ;; d?f) echo 'you typed d-something-f';; * ) echo 'you typed something else entirely,' echo "which happens to have been $answer" ;; esac Like all other control structures, the case statement may be used from either the command line or a script. The case...esac statement is described in more detail in the UserMan.doc file; please see that document for details. SKsh Amiga Shell Page 2 Addendum to 1.4 complist command added The SKsh file name completion mechanism has been extended to handle arbitrary strings. SKsh maintains an internal list of strings and performs command line completion on these strings before performing filename completion. This mechanism, which is described in more detail in the reference manual, allows the following: * A user defined list of completion strings can be maintained to contain, for example, device or program names (such as "graphics:" or "calculator") which are commonly typed. * The completion list can contain programs which are found in the search path. * The completion list can buffer the contents of the current directory so that subsequent successful completions do not have to read the directory. This makes filename completion usable on a floppy based system or on a hard disk when a directory contains a large number of files. A shell function is supplied in the Stuff.sksh file which adds the files in the current directory to the completion list. * Another function provided in the Stuff.sksh file adds file names stored in a .zoo file to the completion list. With a little work, the same mechanism could be extended to .arc or .lzh files. A new 'C' option has been added to turn this feature on or off; see the options command for details. The complist command is described in more detail in the Reference.doc manual; see that document for more information. Resident command support SKsh now uses the ARP resident program standard. A "resident" command has been added which allows programs to be made resident or removed from the resident list. The resident list can also be listed. External commands now smaller, faster The SKsh external commands have been significantly improved both in size and performance over their 1.3 counterparts. The following table gives a rough indication of performance increases; times will, of course, vary depending on drive controllers, disk buffers, other tasks running, etc. All times are in seconds, and include time necessary to load the command itself from disk: SKsh Amiga Shell Page 3 Addendum to 1.4 f1 = 438522 byte, 51348 line ascii file f2 = 426368 byte binary file f3 = 12239 byte binary file Command 1.3 1.4 --------------------------------------------------------- wc f1 >nil: 40 10 wc -c f1 >nil: 30 2 head -20000 f1 >nil: 20 3 tail -1000 f1 >nil: 30 1 (1) cp f1 ram: 47 4 cp -n f1 nil: 44 2 strings f2 >nil: 43 17 cmp -s f2 f2 60 8 cmp -s f2 ram:f2 48 6 xd f3 >nil: 3 4 crc f2 >nil: n/a 7 fgrep 'the' f1 >nil: n/a 31 (2) grep 'the' f1 >nil: n/a 94 (2) (1) Difference mainly due to change in algorithm (2) Lattice grep is 103 seconds The commands are also much smaller in 1.4, averaging about half their previous size. However, they now require the arp.library. Make sure you re-install the new commands in place of the old ones. Some external commands pure Some of the SKsh external commands are now pure, and can be made resident. To use this feature, set the pure bit on the following files: cmp cp du head srun strings view wc window xd This can be accomplished with the SKsh "chmod" command. The other external SKsh binaries can *not* be made resident; a bug in the Lattice C compiler currently prevents that. However, in a future release of SKsh, all of the external binaries may be pure. SKsh Amiga Shell Page 4 Addendum to 1.4 Backslash escape handling changed SKsh backslash escape handling has been changed to be more compatible with Un*x. Previously, a wildcard had to be single or double quoted to turn off its magic properties; now, it can be backslash escaped: [prompt]: echo \* \*.\* * *.* Filename completion escapes wildcard characters If command line filename completion is used to complete a file which contains wildcard characters in the name (for example, a file called "foo*bar", the completion mechanism will automatically escape the wildcard character. For example, "foo\*bar" would be inserted in the command line, which is most often the desired string, since it will match only the proper file. Variable substitution mechanism changed All versions of SKsh prior to 1.4 treated unquoted strings with imbedded variables (such as foo$bar) different than unquoted strings which contained only a variable expansion (such as $bar). This often led to odd results; for example, in version 1.3: [prompt]: foo=blah [prompt]: echo "$foo.ZZZ" blah.ZZZ [prompt]: echo $foo.ZZZ blah .ZZZ <-- notice the extra space SKsh 1.4 treats imbedded variable names the same as non- imbedded variables: [prompt]: foo=blah [prompt]: echo "$foo.ZZZ" blah.ZZZ [prompt]: echo $foo.ZZZ blah.ZZZ SKsh Amiga Shell Page 5 Addendum to 1.4 Variables can now easily be concatenated to text In SKsh 1.3, there was no easy way to concatenate the value of a variable with some text. For example, if a variable named "blah" had some value ("ZZZ"), then "$blahAAA" would be an empty string, since the entire text ("blahAAA") was taken to be a variable name. If it is really desired to concatenate "AAA" to the value of the "blah" variable, it can now be done as follows: [prompt]: blah=ZZZ [prompt]: a=$blah\AAA [prompt]: echo $a ZZZAAA This avoids the ugly construct of: [prompt]: a=$(echo -c $blah AAA) However, the normal backslash escapes ("\n", etc.) take precedence over this mechanism. New 'v' option flag added for variable/wildcard expansion A new 'v' option flag has been added which controls the expansion of variables which contain wildcard characters. The easiest way to illustrate this is with an example. Consider a directory containing 3 files, "a.foo", "blah.foo", and "c.bar": [prompt]: options -v; dum='*' [prompt]: echo $dum.foo *.foo [prompt]: options +v [prompt]: echo $dum.foo a.foo blah.foo In the second "echo" statement, the value of "dum" (which happens to be the wildcard character "*") is used for wildcard expansion. In the first case, (with the "v" flag reset), it is not; the '*' is substituted as is. The "v" flag is reset by default, as this is the Un*x behavior. Directory expansion bug fixed A somewhat obscure bug in the directory expansion mechanism that evaded detection until now has been fixed. If "nested" wildcards (such as */*) were used in a shell command, and the top level directory contained both sub- directories and files, SKsh would often crash if the number of arguments was large (more than 20 or so). It no longer does this. The following command now works correctly, even for a large number of files: SKsh Amiga Shell Page 6 Addendum to 1.4 chmod +wd * */* */*/* Internal SKsh commands have no fixed limit on the number of files which can be matched by a wildcard expansion; there could be thousands, limited only by memory. However, external binaries are still limited by AmigaDos to 255 character command lines. fgrep, grep commands added Two text search commands have been added which provide nearly all the options of their Un*x equivalents. Only the '-b' (block) option is not supported in SKsh. See the documentation on those commands for details. srun command added The srun command allows other commands to be run in the background. It differs from the AmigaDos run command (and similar utilities such as RunBack) in that standard input and output can be redirected, and stack size and priority set for the background command. It is useful in scripts or from the command line when a background command will use the AmigaDos pipe: device. See the documentation on srun for details. view command added The view command is a logical extension of the Un*x file utility. view will attempt to guess a file's type based upon either the contents of the file or the file's name. It will then carry out a user defined action based upon that file type; for example, it might invoke "show" on an IFF bitmap file, "xd" on a binary file, "zoo -list" on a zoo archive, or "lharc v" on an lharc archive. Its actions are based on a configuration file so that new file types can be added as they appear. view is easy to use but somewhat complex to set up; the view "magic" file will have to be customized to your specific system configuration. See the View.doc file for details. tee command added The tee command simply copies its standard input to its standard output and also to any files named in the argument list. It normally overwrites the files, but can also append. See the documentation on the tee command for details. SKsh Amiga Shell Page 7 Addendum to 1.4 crc command added crc is a small utility which computes several 32 bit codes based upon a file's contents. This is often useful to check the integrity of data moved across a questionable transmission medium. du command added The du command prints disk usage information for a set of directory subtrees. It is similar in operation to the Un*x command of the same name, although it is more flexible. See the documentation for details. cp now an external command The cp command is now an external binary, not a shell builtin as in SKsh 1.3. This was done both to improve the speed of the cp command and to reduce the size of the SKsh binary so that new functions could be added. Update option added to cp The cp command now supports an update option (-u) which will copy source files to destination files only if the source file is newer or the destination file does not exist. Clone option changed for cp cp previously required the '-c' option if a clone copy was to be made. This is now the default; the '-n' option can be used to turn this behavior off. cp bugs fixed A few bugs in the cp command were fixed. For example, cp - r used to complain if the destination directory existed. It no longer does this. LLMIN variable added LLMIN filters lines which are added to the history list; any line which is shorter than LLMIN characters long will not be added unless the 'h' options is set. SKsh Amiga Shell Page 8 Addendum to 1.4 MAXDIST variable added The MAXDIST variable also controls the history list. When a line is entered from the keyboard (whether it has been edited or not), SKsh will search backwards through the history list for one just like it. If a line is found in the last MAXDIST commands, the new one is not entered into the history list (unless the 'h' option is set). If the line is not found, or is found greater than MAXDIST commands away, it is re-entered. This prevents commonly used commands from disappearing off the beginning of the history list. Exit performance improved SKsh previously took a few seconds to exit; this has been improved, and it now exits nearly instantly. Filename expansion bug fixed There was previously a bug in the command line filename expansion code which changed a leading '..' to a slash. (For example, "../foo" would become "/foo"). This has been fixed. In addition, a leading slash will no longer be converted to a ':', although this did not cause any problems. An unrelated but similar bug was changing "..file" to "/file", even though there was no slash between the ".." and "file". This no longer happens. ROOT variable added If Un*x style filename mapping is enabled, SKsh now has the ability to use a user-customized root. For example, if the ROOT variable is set to ':' (as it is by default), a path beginning with a slash will use the root of the current device. If ROOT is set to 'dh0:', the filespec "/foo" would specify a file called "foo" which was on the hard drive, even if the current working directory was on a ram or floppy disk. If ROOT is set to 'dh0:usr/src/' (the trailing slash is important), path names will be relative to that directory. Filename completion will work as expected with the defined ROOT. SKsh Amiga Shell Page 9 Addendum to 1.4 ^d line editing bug fixed. In previous versions of SKsh, a ^d which was used to delete the last character in a line would cause "*** break" to be printed when the next command was entered. This no longer happens. cat bug fixed The SKsh 1.3 cat command would not print the last line of a file if that line had no trailing newline character. This has been fixed. Stack requirements downgraded to 10k bytes. The minimum permitted stack size has been downgraded from 16K to 10K bytes. It may be reduced again in future versions. The previous 16K size was mostly due to an over- zealous requirement. It is possible, but very unlikely, that the 10K size will be exceeded; if this should happen, simply increase the size. It should not be a problem for most users. Additional error code added SKsh now has two error codes for programs which cannot be executed. "Command not found" is reported if the command cannot be located in the search path. If a file of the same name is found, but it cannot be executed, then "Unable to execute program" is reported. Function key text now appended to line Text inserted from a function key is now appended to the end of the command line instead of replacing the old command line. This is often more useful. LASTRC variable added A LASTRC variable has been added which is similar to the existing $? variable. $? contains the return code from the last command, whether that command was external or internal (such as a echo statement or while loop). $LASTRC contains the return code from the last external command; it is not reset by internal return codes. Also, one point about return codes may not be clear; even complex statement have a return code. For example, the return code from an "if" statement is the return code from SKsh Amiga Shell Page 10 Addendum to 1.4 the last statement executed inside the "if". This can occasionally be useful. The same applies for all other shell constructs. Lattice date functions no longer used SKsh 1.3 used the Lattice date functions to display the date and time for files and directories. However, the Lattice functions contained a bug which often caused the day to be off by one. SKsh 1.4 does not use the Lattice date functions, so this bug no longer appears. Documentation updates As always, I have tried to keep the UserMan.doc and Reference.doc documents up to date with the latest changes and additions. A new View.Doc file has been added which documents the view command, and the TinySKsh.doc file describes tiny_sksh. New Files A sample view.magic file has been included which can be used with the view command. However, it will have to be modified to suit your specific system configuration (for example, it must be told about which program you wish to use to view IFF bitmap files). See the View.doc file for details. SKsh binary size reduced I did some tuning of the SKsh code which reduced the size of the binary by about 10K. The new SKsh 1.4 features take about 5K of this, making the SKsh 1.4 binary about 5K smaller than the 1.3 binary. Notes I am now distributing the SKsh archive in both zoo and lharc format. The zoo files are easier to deal with in Un*x, while lharc provides better compression. I have modified the copyright notice in the UserMan.doc file to cover several new cases including uploading SKsh to pay- for-use computer systems (which is basically allowed except if that system tries to claim any rights over SKsh), and magazine/disk services which package PD or shareware software and sell it, often with a magazine (which is basically *not* allowed except under unusual circumstances). Please re-read SKsh Amiga Shell Page 11 Addendum to 1.4 the copyright notice if you think any of these cases might apply to you. Also, note that I make a distinction between the magazine/disk services and PD/shareware disk collections such as the one compiled by Fred Fish. I place much harsher restrictions on the magazine/disk services. SKsh 1.4 includes an extremely non-robust implementation of "real" pipes using the '|' shell syntax. It is turned off by default (and the old method is used). The non-robustness is due exclusively to the two different AmigaDos I/O methods (see the Addendum1.3.doc file for a small discussion of this). If you wish to play with the real pipes, read the readme.pipe file included with this distribution. However, please understand that there are several problems, and this feature is not yet intended for normal use. I had told several people that the arp.library would be distributed with SKsh 1.4. However, upon examining the arp distribution notice, I discovered that this is not practical. The entire arp archive must be included unmodified, and I must place restrictions on the distribution of any SKsh archives which contain the arp archive. I must also register the location of all sites having SKsh with arp. For these (and a few other) reasons, I opted not to include the arp.library here. I would again like to thank everyone who responded with ideas, suggestions, and bug reports. While I could not, of course, implement them all, I have made a reasonable dent in the list. This feedback continues to be an important source of improvements. I would also like to thank Fred Fish, who maintains a compilation of freely distributable Amiga software, and Tad Guy, who modederates the comp.binaries.amiga usenet group through which SKsh is distributed. SKsh Amiga Shell Page 12 Addendum to 1.4