change.log

一本完整的描述Unix Shell 编程的工具书的所有范例

13) In "Bash, Version 2" chapter:
    Added an exercise to "resistor-inventory.sh" exercise.

14) In "Loops and Branches" chapter:
    At "while loops" discussion, added paragraph to final *note*
    about piping into a loop.
    Added comments to "ex25.sh" example.

15) In "Process Substitution" chapter:
    Added example of comparing the output of a command with different
    options.
    Added example of comparing contents of different directories.

16) In "Debugging" chapter:
    At "trap" entry, added "multiple-processes.sh" example.
    (Thank you, Vernia Damiano.)
    Added comments to "ex76.sh" example.

17) In "Writing Scripts" section of "Exercises" appendix:
    In "Difficult" section, added "Word Ladders" exercise .

18) Minor cleanups and fixups to various scripts.

19) In "Bibliography" section:
    Added entries for comp.os.unix.sh and comp.os.unix FAQs.




Version 2.5
'STARFRUIT' release, 02/15/04

1) In "I/O Redirection Chapter":
   At discussion of redirection of multiple output streams,
   Added information about order of operations being important.
   (Thanks, Paulo Marcel Coelho Aragao.)

2) In "Redirecting Code Blocks" section of "I/O Redirection" chapter:
   Fixed error in comment in example "redir4.sh."
     Old = # More concise is     line_count=$(wc < "$Filename")
     New = # More concise is     line_count=$(wc -l < "$Filename")
   Simplified example "redir2a.sh."
   (Thanks, Paulo Marcel Coelho Aragao, for all of the above.)

3) In "Here Documents" chapter:
   Minor rewrite of beginning paragraphs.
   Clarified comment in "generate-script.sh" example.
   Amended warning near end of chapter to include trailing whitespace
   on a "limit string" line, as well as leading whitespace. Added
   explanatory paragraph.
   Noted that the "-" option marking a limit string suppresses only leading
   tabs. Modified comments in "ex71a.sh" example to reflect this.
   (Thanks, Paulo Marcel Coelho Aragao, for all of the above.)
   Fixed two minor errors in "self-document.sh" example script.
   (Thanks, Markus Wolf.)


4) In "Command Substitution" chapter:
   Added footnote at beginning of chapter giving technically correct
   explanation of what happens.
   Added link in first footnote.
   Noted that `...` and $(...) treat a "\\" differently..
   (Thanks, Paulo Marcel Coelho Aragao, for pointing this out.)

5) In "System and Administrative Commands" chapter:
   At "passwd" entry:
     Fixed typo (omitted word "command").
     Added mention of "-l," "-u," and "-d" options.
     Broke out "setnew-passwd.sh" as an external example.
   Moved "MAKEDEV" entry to just below "mknod."
   Added "usermod," "groupmod," "iwconfig,"
  "lsusb / usbmodules," "modinfo," and "setquota" entries.

6) In "Basic Commands" section of "External Commands" Chapter:   
   At "rm" entry, added note about removing filenames beginning with
   a dash.

7) In "Communications Commands" section of "External Commands" chapter:
   Added "chfn" entry.

8) In "Complex Commands" section of "External Commands" Chapter:   
   At "xargs" entry, added "kill-byname.sh" example script.

9) In "Complex Functions and Function Complexities" chapter:
   section of "Functions" chapter:
     In discussion of capturing output of a function, corrected reference
     of "parameter substitution" to "command substitution."
     In "max2.sh" example, corrected typo and misleading comment.
     In "count_lines_in_etc_passwd" in-line example, added comment.
     In "ref-params.sh" example, added comment (almost) clarifying
     a particularly difficult construct. (Paulo Marcel Coelho Aragao)

     Modified note about being unable to dereference passed parameter to
     a function. Removed "note" and made it into an ordinary paragraph.
     Added "ind-func.sh" example of passing an indirect reference to a
     function. Added Bruce W. Clare's "dereference.sh" example of
     dereferencing a parameter passed to a function.

10) In "Assorted Tips" section of "Miscellany" chapter:
    At discussion of using stdout to capture function "return value(s),"
    added parenthetical clarification.

11) In "Regular Expressions" chapter:
    Removed specific reference tying UNIX to use of REs.
    Noted that GNU tools allow extended REs if escaped.
    Removed brackets from RE character sets where unnecessary and
    misleading.
    In "Globbing" Section:
    Corrected note about 'echo' performing wildcard expansion.
    (Thanks, Paulo Marcel Coelho Aragao, for all of the above.)
    Broke 'echo' filename expansion examples out of main "screen" block.

12) In "Arithmetic Expansion" chapter:
    At in-line example code,
      Fixed comment about quotes enclosing "special characters."
      Noted that within double parens, parameter dereferencing is optional.
    (Thanks, Paulo Marcel Coelho Aragao.)

13) In "Gotchas" chapter:
    Fixed "bad-op.sh" example (misuse of string comparison
    operators). Added much additional explanatory material to it.
    Broke it out as an external example.
    (Thanks, Paulo Marcel Coelho Aragao, for the hint.)

14) In "Subshells" chapter:
    Additional comment at code snippet for testing whether a
    variable is defined.
    Modification of code snippet testing for a lock file.
    (Thanks, Paulo Marcel Coelho Aragao, for both of the above.)

15) In "/dev and /proc" chapter:
    Added Troy Engel's "dev-tcp" example script.

16) In "Bibliography" section:
    Added "Mastering Regular Expressions (Friedl)" reference.
    (Thanks, Paulo Marcel Coelho Aragao, for the suggestion.)
    Added reference to William Park's Bash enhancement project.

17) In "Contributed Scripts" appendix:
    Did some very minor polishing on "days-between.sh" script.
    Added Troy Engel's "archiveweblogs.sh" example.

18) In "Writing Scripts" section of "Exercises" appendix:
    Added "Logging Logins" problem to "Intermediate" section.
    Added optional section to "Word-Find" problem.
    Fixed typo in "Playfair Cipher" problem.

19) Added "Important System Directories" appendix.

20) At various points in the text, corrected maximum return value
    of a function to 255 (was 256).




Version 2.4
'MUSKMELON' release, 01/25/04

1) In "Loops and Branches" chapter:
   Fixed comment in "continue-nlevel.sh" example.
   Minor fine-tuning of "bin-grep.sh" example.
   Added comment to "symlinks.sh" example.
   (Thanks, Paulo Marcel Coelho Aragao, for all of the above.)

2) In "Operations and Related Topics" chapter:
   Added counting method in "arith-ops.sh" example.
   (Thanks, David Lombard.)
   Minor comment addition to "and-or.sh" example.

3) In "Internal Commands and Builtins" chapter:
   Fixed error in comment in "ex44.sh" example.
   Corrected discussion at "getopts" entry.
   (Thanks, Paulo Marcel Coelho Aragao.)
   Fixed comment misnaming $IFS.
   (Thanks, Mike Latimer.)

4) In "$RANDOM" section of "Variables Revisited" chapter:
   Simplified dice throw section of "ex21.sh" example.
   Alternate formula in "random-between.sh" example.
   (Thanks, Paulo Marcel Coelho Aragao, for both of the above.)

5) In "Arithmetic Expansion" chapter:
   Added use of (( stand-alone expression )) to in-line
   usage example.

6) In "Basic Commands" section of "External Commands" Chapter:   
   At "ln" entry, added "hello.sh" example
   (link at "$0" entry in "Special Variable Types" section
   of "Introduction to Variables and Parameters" chapter.)

7) In "File and Archiving Commands" section of "External Commands" Chapter:
   Fixed error in command-line args check in "strip-comments.sh" example.
   Removed unnecessary 'eval' from "strip-comments.sh" example.
   (Thanks, Paulo Marcel Coelho Aragao, for both of the above.)
   Fixed a subtle logic error in "file-integrity.sh" example.
   (Thanks, Paulo Marcel Coelho Aragao, for bringing the error
   to my attention.)

8) In "Communications Commands" section of "External Commands" chapter:
   Clarified explanation of "ipcalc" entry.
   Corrected "ping" entry.
   (Thanks, Paulo Marcel Coelho Aragao, for directing my attention
   to these.)

9) In "Complex Commands" section of "External Commands" Chapter:   
   Added comment to "ex57.sh".
   (Thanks, Paulo Marcel Coelho Aragao.)

10) In "Internal Variables" section of "Variables Revisited" chapter:
    Changed description of "$IFS" entry to correctly read "internal
    field separator.
    (Thanks, Mike Latimer.)
    Added short introductory paragraph to "$IFS" entry.

11) In "System and Administrative Commands" chapter:
    Renamed "crond" entry to the more traditional "cron,"
    and noted that "crond" is Matthew Dillon's version.
    Added explanatory notes to "id" and "logname" entries.
    (Thanks, Paulo Marcel Coelho Aragao, for all of the above.)

12) In "Math Commands" section of "External Commands" chapter:
    Added Paulo Mercel coelho Aragao's comment to "base.sh" example.

13) In "Time/Date Commands" section of "External Commands" chapter:
    Simplified "ex51.sh" example by eliminating an unnecessary 'eval.'
   (Thanks, Paulo Marcel Coelho Aragao.)

14) In "Miscellaneous Commands" section of "External Commands" Chapter:   
    Cleaned up in-line example at "mcookie" entry.
    Corrected description of "objdump" entry.
    Corrected "getopt" entry.
   (Thanks, Paulo Marcel Coelho Aragao.)

15) In "Text Processing Commands" of "External Commands and Filters"
    chapter:
    Added comment to in-line example at "grep" entry.

16) In "Functions" chapter:
    Added material to "ex59.sh" example.

17) In "Tests" chapter:
    Added "if grep" example at "if" entry.
    (Thanks, Michel Briand.)

18) In "Here Documents" chapter:
    Added comment block to "ex71.sh",
    explaining how to redirect stdout to a file.
    Added in-line example of setting a variable
    from the output of a here document.
    (Thanks, Jason Parker, for both of the above.)

19) In "Arrays" chapter:
    Fixed errors in comments in in-line "Nested Array" example.
    Added clarification and comments to "array-assign.bash" example.
    (Thank you, William Park, for both of the above.)
    After "array-assig.bash" example, added note about speeding up
    execution using an "unnecessary" 'declare -a' in an array declaration.

20) In "Gotchas" chapter:
    Added problem with "tail -f" piped to a "grep" while trying to
    write the stdout to a file.
    (Thanks, TKVoice Author, for bringing this to my attention.)

21) In "Options" chapter:
    Minor revisions to "Bash options" table.

22) In "Revision History" appendix:
    Changed format to a table.

23) Restored truncated version of Revision History to front matter.
    It turns out that this is required Docbook metadata, per the LDP.
   



Version 2.3
'STRAWBERRY' release, 12/28/03

1) In "Parameter Substitution" section of "Variables Revisited" chapter:
   Fixed typo ("code code") at "${parameter=default}" entry.
   (Thank you, Ken Harrenstien.)
   Simplified usage example of "${var#Pattern}.
   Added more elaborate alternate.
   (Thank you, Manfred Schwarb.)

2) In "Operations and Related Topics" chapter:
   Noted that as of version 2.05b, Bash supports 64-bit integers.
   (Thank you, Ken Harrenstien.)

3) In "Options" chapter:
   Clarified "single-dash" versus "double-dash" invocation of options.

4) In "Internal Commands" chapter:
   Applied fix to "eval.example" example.
   (Thanks, Paulo Marcel Coelho Aragao.)

5) In "Text Processing Commands" of "External Commands and Filters" chapter:
   Modified "wf.sh" example to also filter out commas.

6) In "Basic Commands" section of "External Commands" Chapter:   
   At "ln" discussion, fixed error and added John MacDonald's lucid
   explanation of the difference between a hard and soft link.

7) In "Complex Commands" section of "External Commands" Chapter:   
   At "xargs" discussion, added "wf2.sh" example script.

8) In "Special Characters" chapter:
   Modified "ex58.sh" example to include creation date in name of
   backup file. (Thanks, Joshua Tschida.)
   Added listing for "Ctl-Q." (Thanks, Jeremy Weatherford.)
   Fixed erroneous comment at ": >>" entry. (Thanks, Mitchlan Landers.)

9) In "Time/Date Commands" section of "External Commands" chapter:
   At "date" discussion, added "ex58" cross-reference
   and using "date" to generate 6-digit random integers.

10) Bash, version 2.05b, no longer supports large negative integer
    return values. This required changing some text and rewriting the
    example scripts "max2.sh" and "return-test.sh" in the "Functions"
    chapter. Also, the "days-between.sh" script in the "Contributed
    Scripts" appendix needed modification. It serves me right for
    using undocumented features.

11) In "Functions" chapter:
    Added subsection on recursion in a function, without using local
    variables. Added Amit Singh's wonderfully recursive "Towers of Hanoi"
    (hanoi.bash) example script.

12) In "Gotchas" chapter:
    Added discussion of hazards of using undocumented features in Bash.

13) In "Internal Variables" section of "Variables Revisited" chapter:
    Revised discussion of "$TMOUT" variable to reflect
    changes in version 2.05b of Bash. Provided inline usage example.

14) In "Here Documents" chapter:
    Minor stylistic change in introductory paragraph.

15) In "Globbing" section of "Regular Expressions" chapter:
    Added discussion of changing globbing behavior using "set -f" and
    "nocaseglob" and "nullglob" options to 'shopt.'

16) In "Arrays" chapter:
    Fixed error in comment in "array-ops.sh" example.
    (Paulo Marcel Coelho Aragao and Emilio Conti both pointed this out.)
    Fixed error in comment in "array-strops.sh" example.
    (Thanks, Paulo Marcel Coelho Aragao.)
    Fixed misleading comment in "ex67.sh" example,
    and added comment about use of "@" and "*" in array notation
    being analogous to $@ and $*.
    (Thanks, Paulo Marcel Coelho Aragao.)
    Removed unnecessary instances of "declare" from "empty-array.sh"
    example.
    (Thanks, Paulo Marcel Coelho Aragao.)
    Simplified in-line example demonstrating loading of the contents
    of a file into an array.
    (Thanks, Paulo Marcel Coelho Aragao.)
    Added comments suggesting a simplification in "bubble.sh" example.
    (Thanks, Paulo Marcel Coelho Aragao.)

17) In "Contributed Scripts" appendix:
    Added Konstantin Riabitsev's "usb.sh" example.
    Fortunately, the script is GPL, which is compatible
    with the ABS Guide license.