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Shellorama 2002

[Nov 1, 2002] bash-2.05b.tar.gz is now available. NEWS

d.  `select' was changed to be more ksh-compatible, in that the menu is  reprinted each time through the loop only if REPLY is set to NULL.   The previous behavior is available as a compile-time option.

e.  `complete -d' and `complete -o dirnames' now force a slash to be appended to names which are symlinks to directories.

g.  Added support for ksh93-like [:word:] character class in pattern matching.

h.  The  $'...' quoting construct now expands \cX to Control-X.

i.  A new \D{...} prompt expansion; passes the `...' to strftime and inserts  the result into the expanded prompt.

j.  The shell now performs arithmetic in the largest integer size the  machine supports (intmax_t), instead of long.

k.  If a numeric argument is supplied to one of the bash globbing completion  functions, a `*' is appended to the word before expansion is attempted.

l.  The bash globbing completion functions now allow completions to be listed  with double tabs or if `show-all-if-ambiguous' is set.

m.  New `-o nospace' option for `complete' and `compgen' builtins; suppresses   readline's appending a space to the completed word.

n.  New `here-string' redirection operator:  <<< word.

o.  When displaying variables, function attributes and definitions are shown  separately, allowing them to be re-used as input (attempting to re-use the old output would result in syntax errors).

r.  `read' has a new `-u fd' option to read from a specified file descriptor.

u.  The `printf' %q format specifier now uses $'...' quoting to print the  argument if it contains non-printing characters.

v.  The `declare' and `typeset' builtins have a new `-t' option.  When applied to functions, it causes the DEBUG trap to be inherited by the named function.  Currently has no effect on variables.

w.  The DEBUG trap is now run *before* simple commands, ((...)) commands,   [[...]] conditional commands, and for ((...)) loops.

z.  New [n]<&word- and [n]>&word- redirections from ksh93 -- move fds (dup
    and close).

bb. The `hash' builtin has a new `-l' option to list contents in a reusable format, and a `-d' option to remove a name from the hash table.

dd. All builtins that take operands accept a `--' pseudo-option, except  `echo'.

2.  New Features in Readline

a.  Support for key `subsequences':  allows, e.g., ESC and ESC-a to both   be bound to readline functions.  Now the arrow keys may be used in vi   insert mode.

h.  Readline now has an overwrite mode, toggled by the `overwrite-mode' bindable command, which could be bound to `Insert'.

i.  New application-settable completion variable: rl_completion_suppress_append, inhibits appending of rl_completion_append_character to completed words.

j.  New key bindings when reading an incremental search string:  ^W yanks the currently-matched word out of the current line into the search string; ^Y yanks the rest of the current line into the search string,     DEL or ^H deletes characters from the search string.

-------------------------------------------------------------------------------
This is a terse description of the new features added to bash-2.05a since the release of bash-2.05.  As always, the manual page (doc/bash.1) is the place to look for complete descriptions.

g.  New `\A' prompt string escape sequence; expands to time in 24 HH:MM format.

h.  New `-A group/-g' option to complete and compgen; does group name  completion.

i.  New `-t' option to `hash' to list hash values for each filename argument.

j.  New [-+]O invocation option to set and unset `shopt' options at startup.

l.  The ksh-like `ERR' trap has been added.  The `ERR' trap will be run   whenever the shell would have exited if the -e option were enabled.   It is not inherited by shell functions.

m.  `readonly', `export', and `declare' now print variables which have been  given attributes but not set by assigning a value as just a command and a variable name (like `export foo') when listing, as the latest POSIX  drafts require.

p.  `for' loops now allow empty word lists after `in', like the latest POSIX  drafts require.

q.  The builtin `ulimit' now takes two new non-numeric arguments:  `hard',  meaning the current hard limit, and `soft', meaning the current soft  limit, in addition to `unlimited'
   
r.  `ulimit' now prints the option letter associated with a particular  resource when printing more than one limit.

s.  `ulimit' prints `hard' or `soft' when a value is not `unlimited' but is  one of RLIM_SAVED_MAX or RLIM_SAVED_CUR, respectively.

t.  The `printf' builtin now handles the %a and %A conversions if they're implemented by printf(3).

u.  The `printf' builtin now handles the %F conversion (just about like %f).

v.  The `printf' builtin now handles the %n conversion like printf(3).  The   corresponding argument is the name of a shell variable to which the  value is assigned.

2.  New Features in Readline

a.  Added extern declaration for rl_get_termcap to readline.h, making it a
    public function (it was always there, just not in readline.h).

b.  New #defines in readline.h:  RL_READLINE_VERSION, currently 0x0402,
    RL_VERSION_MAJOR, currently 4, and RL_VERSION_MINOR, currently 2.

c.  New readline variable:  rl_readline_version, mirrors RL_READLINE_VERSION.

d.  New bindable boolean readline variable:  match-hidden-files.  Controls  completion of files beginning with a `.' (on Unix).  Enabled by default.

e.  The history expansion code now allows any character to terminate a  `:first-' modifier, like csh.

f.  New bindable variable `history-preserve-point'.  If set, the history  code attempts to place the user at the same location on each history  line retrived with previous-history or next-history.

[Sept 17, 2002] BASH with Debugger and Improved Debug Support and Error Handling

The Bash Debugger Project contains patched sources to BASH that enable better debugging support as well as improved error reporting. In addition, this project contains the most comprehensive source-code debugger for bash that has been written.

Since this project maintains as an open CVS development and encourages developers and ideas, the space could be also be used springboard for other experiments and additions to BASH. If you are interesting in contributing to this project, please contact rocky@panix.com.

However, if you are looking for the plain vanilla BASH, try here.

Documentation On-line documentation.
Download Get the latest version here.
CVS Browse the CVS Tree
Sourceforge The sourceforge.net project page.

[Jul 18, 2002] The GNU Bourne-Again Shell bash 2.05 is now available; most important NEWS:

GNU shtool 1.6.1 Ralf S. Engelschall Saturday, July 13th 2002 15:28 EDT

About: GNU shtool is a compilation of small but very stable and portable shell scripts into a single shell tool. All ingredients were in successful use over many years in various free software projects. The compiled shtool program is intended to be used inside the source tree of free software packages. There it can overtake various (usually non-portable) tasks related to the building and installation of an free software package.

Changes: The non-existent --min-size option was removed from the usage of "shtool rotate". The following was ported to the POSIX 1003.1-2001 (SUSv3) standard: sh.echo, sh.version, sh.path, sh.subst. Various typos in shtool.pod were fixed.

Version Focus Date
1.6.1 Minor bugfixes 13-Jul-2002 15:28

5 Bash tips every Linux user should know - Aug 22, 2001

  1. Finding your history the easy way When using the up arrow key, there is the problem of, "When was the last time I typed that command?" If you know that you have typed the command in the last few days but you don't want to use the up arrow 400 times to find it, there are two simple ways to find your command. The first is with the  history and grep commands. The next time you find yourself in such a situation, type:

    history|grep -i first few letters of command

    This will read the history file (located in ~/.history) and perform a case insensitive search on the command you are looking for. Here is example output from my machine:

         [jd@jd bash]$ history|grep -i POSTGRES
     29  cvs update -d postgres
     30  cd postgres/
     61  cd projects/postgres/

    I now have a list of commands that match my requirements. If the command is in the list, I can use the ! key to execute one of the commands. If I wanted to execute dvips -f practicalpostgresql.dvi -o practicalpostgresql.ps, for example, I could just type !73 which is the corresponding history number with the command I want to execute. The second method of finding the command you are looking for is to use history completion, which is discussed next.
     

  2. History completion.The next time you need a previously entered command, type ctrl-r and then begin typing the command. You will notice ctrl-r finishes the command for you as you type. If you can remember to use ctrl-r, it will become invaluable for repeating longer commands.
  3. Tab completion. Tab completion is similar to history completion, except that tab completion won't complete a previously run command. Instead, the tab completion will finish the name of a command or file that exists within a directory. If I am at a command prompt and I type cd /usr/local/ but I don't quite remember the name of the next directory in the path I can use the tab key to have Bash auto-complete the name. If there are multiple directories or file available, Bash will beep to indicate that there is not a clear option to complete. It will then display a listing of the available options if you press tab again. Here is example output when using tab completion to enter a directory in

    [jd@jd bash]$ cd /usr/local/
    HancomOffice    Loki_Update     bin             etc             info
    man             prod            soffice
    Loki_Uninstall  appgen          doc             games           lib
    mozilla         sbin            src

  4. Aliasing Is there a command that has several parameters that you use a lot? Here at Command Prompt, we are using Jade to process DocBook XML and SGML. Jade will require numerous parameters on execution. As an example, here is the Jade syntax to process an SGML file, and transform it into HTML.
    
   
    
       
   
    
      
    
      
      jade -E 200 -t sgml -V html-index -d 
      /usr/lib/sgml/stylesheets/nwalsh-modular/html/docbook.dsl 
      practicalpostgresql.sgml 
    
   
    
   
   
    This would be difficult and tiresome to type over and over as 
   you are writing and processing a document. Instead, you can use the 
   
   
   alias bash command. 
   Using the above example we can use the 
   
   alias command like 
   this:
    
   
   
    
      
    
      
      alias pghtml='jade -E 200 -t sgml -V html-index -d 
      /usr/lib/sgml/stylesheets/nwalsh-modular/html/docbook.dsl 
      practicalpostgresql.sgml' 
    
   
    
   
   
    Now, if you type just 
   
   
   pghtml at the 
   command line, it will process the aliased jade command. Place this in your
   
   
   .bash_profile, or 
   else it will not be stored in memory the next time you log in. You can have 
   any amount of aliases that you desire, though they must, of course, have 
   unique names. On my system the output looks like this:
    
   
   
   
    [jd@jd practicalpostgresql]$ alias
    
   alias l='ls'
    
   alias la='ls -A -k'
    
   alias ll='ls -l'
    
   alias ls='ls -F --color=auto'
    
   alias lsd='ls -d */'
    
   alias md='mkdir'
    
   alias p='cd -'
    5. 




[May 17, 2002] Since v2.04, bash has allowed to intelligently 
program and extend its standard completion behavior to achieve complex command 
lines with just a few keystrokes. 



   
Imagine typing ssh [Tab] and being able to complete on hosts 
   from your ~/.ssh/known_hosts files. Or typing man 3 str [Tab] and getting a 
   list of all string handling functions in the UNIX manual. mount system: [Tab] 
   would complete on all exported file-systems from the host called system, 
   while make [Tab] would complete on all targets in Makefile.




[Mar 25, 2002]
UnixReview.com/Shell 
corner  -- some potentially useful scripts.



[Mar 10, 2002] 
Unix pipes -- 
examples of scripts that use pipes. Most examples are pretty trivial. 



GNU shtool - GNU Project - Free Software Foundation (FSF) Several useful 
scripts (bash):




Useless Use 
of Cat Award



   
In a recent thread on comp.unix.shell, the 
   following example was posted by Andreas Schwab as another Useful Use of Cat 
   on a lone file: 

   

      
	{ foo; bar; cat mumble; baz } | whatever


   

   
Here, the contents of the file mumble are 
   output to stdout after the output from the programs foo and
   bar, and before the output of baz. All the 
   generated output is piped to the program whatever. (Read up on 
   shell programming constructs if this was news to you :-)




Advanced 
Bash-Scripting Guide Revision 1.1, 06 January 2002 Daniel Robbins' 
three-part series on bash programming on developerWorks:
Part 1,
Part 2, 
and 
Part 3.


ksh93 rpms:



**** 
Example of ksh profile  that contains interesting but probably non-optimal 
way to distinguish between interactive and non-intractive shells [Feb 2, 2002]




   
ENV='$\{FILE[(\_\$-=0)+(\_=1)-\_\$\{-\%\%*i*\}]\}'
export ENV




Advanced 
Bash-Scripting Guide -- by Mendel Cooper [06 Jan, 2002[



   

      

         Revision 1.1
         06 January 2002
         Revised by: mc
      

      

         Bugfixes, material and 
         scripts added.
      

   

   
This tutorial assumes no previous knowledge of scripting or 
   programming, but progresses rapidly toward an intermediate/advanced level of 
   instruction (...all the while sneaking in little snippets of UNIX wisdom 
   and lore). It serves as a textbook, a manual for self-study, and a 
   reference and source of knowledge on shell scripting techniques. The 
   exercises and heavily-commented examples invite active reader participation, 
   under the premise that the only way to really learn scripting is to write 
   scripts.

   
The latest update of this document, as an archived
   "tarball" including both the SGML source and 
   rendered HTML, may be downloaded from
   
   the author's home site. See the
   
   change log for a revision history.






developerWorks Linux Using Bash shell scripts for function testing



   
"Function testing is the phase during a development cycle 
   in which the software application is tested to ensure that the functionality 
   is working as desired and that any errors in the code are properly handled. 
   It is usually done after the unit testing of individual modules, and before a 
   more thorough system test of the entire product under load/stress 
   conditions." 

   
"There are many testing tools in the marketplace that offer 
   a lot of functionality to help with the testing efforts. However, they need 
   to be obtained, installed, and configured, which could take up valuable time 
   and effort. Bash can help to speed things along."




Functions 
and aliases in bash" also

http://www.linuxgazette.com/issue53/eyler.html 



Variable Mangling in Bash with String Operators LG #57 by Pat Eyler (see 
also 
Variable Mangling in Bash with String Operators) 



   
Have you ever wanted to change the names of 
   many files at once? How about using a default value for a variable if it has 
   no value? These and many other options are available to you through string 
   operators in bash and other bourne shell derived shells. 

   

   String operators allow you to manipulate the contents of a variable without 
   having to write your own shell functions to do so. They are provided through 
   'curly brace' syntax. Any variable can be displayed like this ${foo} without 
   changing its meaning. This functionality is often used to protect a variable 
   name from surrounding characters.

   

   bash-2.02$ export foo=foo

   bash-2.02$ echo ${foo}bar # foo exists so this works

   foobar

   bash-2.02$ echo $foobar # foobar doesn't exist, so this fails

   

   bash-2.02$ 

   

   By the end of this article, you'll be able to use it for a whole lot more. 

   

   There are three kinds of variable substitution:

   
   
I'll talk about the first two and leave command 
   substitution for another article. ... If you're interested in more hints 
   about bash (or other stuff I've written about), please take a look at
   my home page. 





Column 
- Ed Schaefer - The Shell Corner -- Each month UnixReview.com will publish a 
selected script in this column. I will evaluate the submissions and award each 
winner $100.00 courtesy...



   
Welcome to the inaugural edition of the Shell Corner 
   column. The premise of Shell Corner is simple: You, the Unix professional 
   send in your favorite Unix shell script and each month UnixReview.com will 
   publish a selected script in this column. I will evaluate the submissions and 
   award each winner $100.00 courtesy of UnixReview.com. What could be more 
   simple? 

   
Joe Casad, UnixReview.com senior editor, wanted a "shell 
   guru" to author this column, but ended up with me instead. My experience is 
   mostly as a Unix business applications programmer and not as a systems 
   administrator. I feel my attitude is more minimalist than most, and my script 
   evaulations are certain to reflect this. I enjoy scripts that are 
   (relatively) easy to read and well documented. If I have trouble reading a 
   script, chances are I'll quickly go to the next one. 

   
What are the limitations on script submissions? I can think 
   of no limitation, other than length. Use any of the Unix tools such as Perl, 
   awk, sed, etc, as well as high level languages, such as C or C++. I'll even 
   struggle through assembler if you will.... ... ...

   
# tolower.sh: convert file names to lower case
# in the current working directory
# Choose either all the files in a directory or a command-line list
if [ "$#" -gt 0 ]; then
   filelist="$@" # just the files on command line
else
   filelist=`ls` # all files
fi
for file in $filelist; do
# Use the grep command to determine if the file has an upper case letter
# Determine the destination of the mv command by down shifting all the 
# letters in the file name. Command substituting an echo of the 
# file name to the translate filter, tr, performs the downshift
   if echo "$file"|grep [A-Z] > /dev/null; then
      mv "$file" `echo "$file"|tr "[A-Z]" "[a-z]"`
   fi
done   




Bourne Shell Programming by Robert P. 
Sayle 


Some useful shell links 



   



*** Of 
Unix shells and environment variables -- Mo Budlong small tutorial.(2,200 
words)







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Last modified: 
March 15, 2008