Recent user-visible changes to Tcl:

1. No more [command1] [command2] construct for grouping multiple
commands on a single command line.

2. Semi-colon now available for grouping commands on a line.

3. For a command to span multiple lines, must now use backslash-return
at the end of each line but the last.

4. "Var" command has been changed to "set".

5. Double-quotes now available as an argument grouping character.

6. "Return" may be used at top-level.

7. More backslash sequences available now.  In particular, backslash-newline
may be used to join lines in command files.

8. New or modified built-in commands:  case, return, for, glob, info,
print, return, set, source, string, uplevel.

9. After an error, the variable "errorInfo" is filled with a stack
trace showing what was being executed when the error occurred.

10. Command abbreviations are accepted when parsing commands, but
are not recommended except for purely-interactive commands.

11. $, set, and expr all complain now if a non-existent variable is
referenced.

12. History facilities exist now.  See Tcl.man and Tcl_RecordAndEval.man.

13. Changed to distinguish between empty variables and those that don't
exist at all.  Interfaces to Tcl_GetVar and Tcl_ParseVar have changed
(NULL return value is now possible).  *** POTENTIAL INCOMPATIBILITY ***

14. Changed meaning of "level" argument to "uplevel" command (1 now means
"go up one level", not "go to level 1"; "#1" means "go to level 1").
*** POTENTIAL INCOMPATIBILITY ***

15. 3/19/90 Added "info exists" option to see if variable exists.

16. 3/19/90 Added "noAbbrev" variable to prohibit command abbreviations.

17. 3/19/90 Added extra errorInfo option to "error" command.

18. 3/21/90 Double-quotes now only affect space:  command, variable,
and backslash substitutions still occur inside double-quotes.
*** POTENTIAL INCOMPATIBILITY ***

19. 3/21/90 Added support for \r.

20. 3/21/90 List, concat, eval, and glob commands all expect at least
one argument now.  *** POTENTIAL INCOMPATIBILITY ***

21. 3/22/90 Added "?:" operators to expressions.

22. 3/25/90 Fixed bug in Tcl_Result that caused memory to get trashed.

------------------- Released version 3.1 ---------------------

23. 3/29/90 Fixed bug that caused "file a.b/c ext" to return ".b/c".

24. 3/29/90 Semi-colon is not treated specially when enclosed in
double-quotes.

------------------- Released version 3.2 ---------------------

25. 4/16/90 Rewrote "exec" not to use select or signals anymore.
Should be more Sys-V compatible, and no slower in the normal case.

26. 4/18/90 Rewrote "glob" to eliminate GNU code (there's no GNU code
left in Tcl, now), and added Tcl_TildeSubst procedure.  Added automatic
tilde-substitution in many commands, including "glob".

------------------- Released version 3.3 ---------------------

27. 7/11/90 Added "Tcl_AppendResult" procedure.

28. 7/20/90 "History" with no options now defaults to "history info"
rather than to "history redo".  Although this is a backward incompatibility,
it should only be used interactively and thus shouldn't present any
compatibility problems with scripts.

29. 7/20/90 Added "Tcl_GetInteger", "Tcl_GetDouble", and "Tcl_GetBoolean"
procedures.

30. 7/22/90 Removed "Tcl_WatchInterp" procedure:  doesn't seem to be
necessary, since the same effect can be achieved with the deletion
callbacks on individual commands.  *** POTENTIAL INCOMPATIBILITY ***

31. 7/23/90 Added variable tracing:  Tcl_TraceVar, Tcl_UnTraceVar,
and Tcl_VarTraceInfo procedures, "trace" command.

32. 8/9/90 Mailed out list of all bug fixes since 3.3 release.

33. 8/29/90 Fixed bugs in Tcl_Merge relating to backslashes and
semi-colons.  Mailed out patch.

34. 9/3/90 Fixed bug in tclBasic.c: quotes weren't quoting ]'s.
Mailed out patch.

35. 9/19/90 Rewrote exec to always use files both for input and
output to the process.  The old pipe-based version didn't work if
the exec'ed process forked a child and then exited:  Tcl waited
around for stdout to get closed, which didn't happen until the
grandchild exited.

36. 11/5/90 ERR_IN_PROGRESS flag wasn't being cleared soon enough
in Tcl_Eval, allowing error messages from different commands to
pile up in $errorInfo.  Fixed by re-arranging code in Tcl_Eval that
re-initializes result and ERR_IN_PROGRESS flag.  Didn't mail out
patch:  changes too complicated to describe.

37. 12/19/90 Added Tcl_VarEval procedure as a convenience for
assembling and executing Tcl commands.

38. 1/29/91 Fixed core leak in Tcl_AddErrorInfo.  Also changed procedure
and Tcl_Eval so that first call to Tcl_AddErrorInfo need not come from
Tcl_Eval.

----------------- Released version 5.0 with Tk ------------------

39. 4/3/91 Removed change bars from manual entries, leaving only those
that came after version 3.3 was released.

40. 5/17/91 Changed tests to conform to Mary Ann May-Pumphrey's approach.

41. 5/23/91 Massive revision to Tcl parser to simplify the implementation
of string and floating-point support in expressions.  Newlines inside
[] are now treated as command separators rather than word separators
(this makes newline treatment consistent throughout Tcl).
*** POTENTIAL INCOMPATIBILITY ***

42. 5/23/91 Massive rewrite of expression code to support floating-point
values and simple string comparisons.  The C interfaces to expression
routines have changed (Tcl_Expr is replaced by Tcl_ExprLong, Tcl_ExprDouble,
etc.), but all old Tcl expression strings should be accepted by the new
expression code.
*** POTENTIAL INCOMPATIBILITY ***

43. 5/23/91 Modified tclHistory.c to check for negative "keep" value.

44. 5/23/91 Modified Tcl_Backslash to handle backslash-newline.  It now
returns 0 to indicate that a backslash sequence should be replaced by
no character at all.
*** POTENTIAL INCOMPATIBILITY ***

45. 5/29/91 Modified to use ANSI C function prototypes.  Must set
"USE_ANSI" switch when compiling to get prototypes.

46. 5/29/91 Completed test suite by providing tests for all of the
built-in Tcl commands.

47. 5/29/91 Changed Tcl_Concat to eliminate leading and trailing
white-space in each of the things it concatenates and to ignore
elements that are empty or have only white space in them.  This
produces cleaner output from the "concat" command.
*** POTENTIAL INCOMPATIBILITY ***

48. 5/31/91 Changed "set" command and Tcl_SetVar procedure to return
new value of variable.

49. 6/1/91 Added "while" and "cd" commands.

50. 6/1/91 Changed "exec" to delete the last character of program
output if it is a newline.  In most cases this makes it easier to
process program-generated output.
*** POTENTIAL INCOMPATIBILITY ***

51. 6/1/91 Made sure that pointers are never used after freeing them.

52. 6/1/91 Fixed bug in TclWordEnd where it wasn't dealing with
[] inside quotes correctly.

53. 6/8/91 Fixed exec.test to accept return values of either 1 or
255 from "false" command.

54. 7/6/91 Massive overhaul of variable management.  Associative
arrays now available, along with "unset" command (and Tcl_UnsetVar
procedure).  Variable traces have been completely reworked:
interfaces different both from Tcl and C, and multiple traces may
exist on same variable.  Can no longer redefine existing local
variable to be global.  Calling sequences have changed slightly
for Tcl_GetVar and Tcl_SetVar ("global" is now "flags"). Tcl_SetVar
can fail and return a NULL result.  New forms of variable-manipulation
procedures:  Tcl_GetVar2, Tcl_SetVar2, etc.  Syntax of variable
$-notation changed to support array indexing.
*** POTENTIAL INCOMPATIBILITY ***

55. 7/6/91 Added new list-manipulation procedures:  Tcl_ScanElement,
Tcl_ConvertElement, Tcl_AppendElement.

56. 7/12/91 Created new procedure Tcl_EvalFile, which does most of the
work of the "source" command.

57. 7/20/91 Major reworking of "exec" command to allow pipelines,
more redirection, background.  Added new procedures Tcl_Fork,
Tcl_WaitPids, Tcl_DetachPids, and Tcl_CreatePipeline.  The old
"< input" notation has been replaced by "<< input" ("<" is for
redirection from a file).  Also handles error returns and abnormal
terminations (e.g. signals) differently.
*** POTENTIAL INCOMPATIBILITY ***

58. 7/21/91 Added "append" and "lappend" commands.

59. 7/22/91 Reworked error messages and manual entries to use
?x? as the notation for an optional argument x, instead of [x].  The
bracket notation was often confused with the use of brackets for
command substitution.  Also modified error messages to be more
consistent.

60. 7/23/91 Tcl_DeleteCommand now returns an indication of whether
or not the command actually existed, and the "rename" command uses
this information to return an error if an attempt is made to delete
a non-existent command.
*** POTENTIAL INCOMPATIBILITY ***

61. 7/25/91 Added new "errorCode" mechanism, along with procedures
Tcl_SetErrorCode, Tcl_UnixError, and Tcl_ResetResult.  Renamed
Tcl_Return to Tcl_SetResult, but left a #define for Tcl_Return to
avoid compatibility problems.

62. 7/26/91 Extended "case" command with alternate syntax where all
patterns and commands are together in a single list argument:  makes
it easier to write multi-line case statements.

63. 7/27/91 Changed "print" command to perform tilde-substitution on
the file name.

64. 7/27/91 Added "tolower", "toupper", "trim", "trimleft", and "trimright"
options to "string" command.

65. 7/29/91 Added "atime", "mtime", "size", and "stat" options to "file"
command.

66. 8/1/91 Added "split" and "join" commands.

67. 8/11/91 Added commands for file I/O, including "open", "close",
"read", "gets", "puts", "flush", "eof", "seek", and "tell".

68. 8/14/91 Switched to use a hash table for command lookups.  Command
abbreviations no longer have direct support in the Tcl interpreter, but
it should be possible to simulate them with the auto-load features
described below.  The "noAbbrev" variable is no longer used by Tcl.
*** POTENTIAL INCOMPATIBILITY ***

68.5 8/15/91 Added support for "unknown" command, which can be used to
complete abbreviations, auto-load library files, auto-exec shell
commands, etc.

69. 8/15/91 Added -nocomplain switch to "glob" command.

70. 8/20/91 Added "info library" option and TCL_LIBRARY #define.  Also
added "info script" option.

71. 8/20/91 Changed "file" command to take "option" argument as first
argument (before file name), for consistency with other Tcl commands.
*** POTENTIAL INCOMPATIBILITY ***

72. 8/20/91 Changed format of information in $errorInfo variable:
comments such as 
    ("while" body line 1)
are now on separate lines from commands being executed.
*** POTENTIAL INCOMPATIBILITY ***

73. 8/20/91 Changed Tcl_AppendResult so that it (eventually) frees
large buffers that it allocates.

74. 8/21/91 Added "linsert", "lreplace", "lsearch", and "lsort"
commands.

75. 8/28/91 Added "incr" and "exit" commands.

76. 8/30/91 Added "regexp" and "regsub" commands.

77. 9/4/91 Changed "dynamic" field in interpreters to "freeProc" (procedure
address).  This allows for alternative storage managers.
*** POTENTIAL INCOMPATIBILITY ***

78. 9/6/91 Added "index", "length", and "range" options to "string"
command.  Added "lindex", "llength", and "lrange" commands.

79. 9/8/91 Removed "index", "length", "print" and "range" commands.
"Print" is redundant with "puts", but less general, and the other
commands are replaced with the new commands described in change 78
above.
*** POTENTIAL INCOMPATIBILITY ***

80. 9/8/91 Changed history revision to occur even when history command
is nested;  needed in order to allow "history" to be invoked from
"unknown" procedure.

81. 9/13/91 Changed "panic" not to use vfprintf (it's uglier and less
general now, but makes it easier to run Tcl on systems that don't
have vfprintf).  Also changed "strerror" not to reclare sys_errlist.

82. 9/19/91 Lots of changes to improve portability to different UNIX
systems, including addition of "config" script to adapt Tcl to the
configuration of the system it's being compiled on.

83. 9/22/91 Added "pwd" command.

84. 9/22/91 Renamed manual pages so that their filenames are no more
than 14 characters in length, moved to "doc" subdirectory.

85. 9/24/91 Redid manual entries so they contain the supplemental
macros that they need;  can just print with "troff -man" or "man"
now.

86. 9/26/91 Created initial version of script library, including
a version of "unknown" that does auto-loading, auto-execution, and
abbreviation expansion.  This library is used by tclTest
automatically.  See the "library" manual entry for details.

----------------- Released version 6.0, 9/26/91 ------------------

87. 9/30/91 Made "string tolower" and "string toupper" check case
before converting:  on some systems, "tolower" and "toupper" assume
that character already has particular case.

88. 9/30/91 Fixed bug in Tcl_SetResult:  wasn't always setting freeProc
correcly when called with NULL value.  This tended to cause memory
allocation errors later.

89. 10/3/91 Added "upvar" command.

90. 10/4/91 Changed "format" so that internally it converts %D to %ld,
%U to %lu, %O to %lo, and %F to %f.  This eliminates some compatibility
problems on some machines without affecting behavior.

91. 10/10/91 Fixed bug in "regsub" that caused core dumps with the -all
option when the last match wasn't at the end of the string.

92. 10/17/91 Fixed problems with backslash sequences:  \r support was
incomplete and \f and \v weren't supported at all.

93. 10/24/91 Added Tcl_InitHistory procedure.

94. 10/24/91 Changed "regexp" to store "-1 -1" in subMatchVars that
don't match, rather than returning an error.

95. 10/27/91 Modified "regexp" to return actual strings in matchVar
and subMatchVars instead of indices.  Added "-indices" switch to cause
indices to be returned.
*** POTENTIAL INCOMPATIBILITY ***

96. 10/27/91 Fixed bug in "scan" where it used hardwired constants for
sizes of floats and doubles instead of using "sizeof".

97. 10/31/91 Fixed bug in tclParse.c where parse-related error messages
weren't being storage-managed correctly, causing spurious free's.

98. 10/31/91 Form feed and vertical tab characters are now considered
to be space characters by the parser.

99. 10/31/91 Added TCL_LEAVE_ERR_MSG flag to procedures like Tcl_SetVar.

100. 11/7/91 Fixed bug in "case" where "in" argument couldn't be ommitted
if all case branches were embedded in a single list.

101. 11/7/91 Switched to use "pid_t" and "uid_t" and other official
POSIC types and function prototypes.

----------------- Released version 6.1, 11/7/91 ------------------

102. 12/2/91 Modified Tcl_ScanElement and Tcl_ConvertElement in several
ways.  First, allowed caller to request that only backslashes be used
(no braces).  Second, made Tcl_ConvertElement more aggressive in using
backslashes for braces and quotes.

103. 12/5/91 Added "type", "lstat", and "readlink" options to "file"
command, plus added new "type" element to output of "stat" and "lstat"
options.

104. 12/10/91 Manual entries had first lines that caused "man" program
to try weird preprocessor.  Added blank comment lines to fix problem.

105. 12/16/91 Fixed a few bugs in auto_mkindex proc:  wasn't handling
errors properly, and hadn't been upgraded for new "regexp" syntax.

106. 1/2/92 Fixed bug in "file" command where it didn't properly handle
a file names containing tildes where the indicated user doesn't exist.

107. 1/2/92 Fixed lots of cases in tclUnixStr.c where two different
errno symbols (e.g. EWOULDBLOCK and EAGAIN) have the same number;  Tcl
will only use one of them.

108. 1/2/92 Lots of changes to configuration script to handle many more
systems more gracefully.  E.g. should now detect the bogus strtoul that
comes with AIX and substitute Tcl's own version instead.

----------------- Released version 6.2, 1/10/92 ------------------

109. 1/20/92 Config didn't have code to actually use "uid_t" variable
to set TCL_UIT_T #define.

110. 2/10/92 Tcl_Eval didn't properly reset "numLevels" variable when
too-deep recursion occurred.

111. 2/29/92 Added "on" and "off" to keywords accepted by Tcl_GetBoolean.

112. 3/19/92 Config wasn't installing default version of strtod.c for
systems that don't have one in libc.a.

113. 3/23/92 Fixed bug in tclExpr.c where numbers with leading "."s,
like 0.75, couldn't be properly substituted into expressions with
variable or command substitution.

114. 3/25/92 Fixed bug in tclUnixAZ.c where "gets" command wasn't
checking to make sure that it was able to write the variable OK.

115. 4/16/92 Fixed bug in tclUnixAZ.c where "read" command didn't
compute file size right for device files.

116. 4/23/92 Fixed but in tclCmdMZ.c where "trace vinfo" was overwriting
the trace command.

----------------- Released version 6.3, 5/1/92 ------------------

117. 5/1/92 Added Tcl_GlobalEval.

118. 6/1/92 Changed auto-load facility to source files at global level.

119. 6/8/92 Tcl_ParseVar wasn't always setting termPtr after errors, which
sometimes caused core dumps.

120. 6/21/92 Fixed bug in initialization of regexp pattern cache.  This
bug caused segmentation violations in regexp commands under some conditions.

121. 6/22/92 Changed implementation of "glob" command to eliminate
trailing slashes on directory names:  they confuse some systems.  There
shouldn't be any user-visible changes in functionality except for names
in error messages not having trailing slashes.

122. 7/2/92 Fixed bug that caused 'string match ** ""' to return 0.

123. 7/2/92 Fixed bug in Tcl_CreateCmdBuf where it wasn't initializing
the buffer to an empty string.

124. 7/6/92 Fixed bug in "case" command where it used NULL pattern string
after errors in the "default" clause.

125. 7/25/92 Speeded up auto_load procedure:  don't reread all the index
files unless the path has changed.

126. 8/3/92 Changed tclUnix.h to define MAXPATHLEN from PATH_MAX, not
_POSIX_PATH_MAX.

----------------- Released version 6.4, 8/7/92 ------------------

127. 8/10/92 Changed tclBasic.c so that comment lines can be continued by
putting a backslash before the newline.

128. 8/21/92 Modified "unknown" to allow the source-ing of a file for
an auto-load to trigger other nested auto-loads, as long as there isn't
any recursion on the same command name.

129. 8/25/92 Modified "format" command to allow " " and "+" flags, and
allow flags in any order.

130. 9/14/92 Modified Tcl_ParseVar so that it doesn't actually attempt
to look up the variable if "noEval" mode is in effect in the interpreter
(it just parses the name).  This avoids the errors that used to occur
in statements like "expr {[info exists foo] && $foo}".

131. 9/14/92 Fixed bug in "uplevel" command where it didn't output the
correct error message if a level was specified but no command.

132. 9/14/92 Renamed manual entries to have extensions like .3 and .n,
and added "install" target to Makefile.

133. 9/18/92 Modified "unknown" command to emulate !!, !<num>, and
^<old>^<new> csh history substitutions.

134. 9/21/92 Made the config script cleverer about figuring out which
switches to pass to "nm".

135. 9/23/92 Fixed tclVar.c to be sure to copy flags when growing variables.
Used to forget about traces in progress and make extra recursive calls
on trace procs.

136. 9/28/92 Fixed but in auto_reset where it was unsetting variables
that might not exist.

137. 10/7/92 Changed "parray" library procedure to print any array
accessible to caller, local or global.

138. 10/15/92 Fixed bug where propagation of new environment variable
values among interpreters took N! time if there exist N interpreters.

139. 10/16/92 Changed auto_reset procedure so that it also deletes any
existing procedures that are in the auto_load index (the assumption is
that they should be re-loaded to get the latest vesions).

140. 10/21/92 Fixed bug that caused lists to be incorrectly generated
for elements that contained backslash-newline sequences.

141. 12/9/92 Added support for TCL_LIBRARY environment variable:  use
it as library location if it's present.

142. 12/9/92 Added "info complete" command, Tcl_CommandComplete procedure.

143. 12/16/92 Changed the Makefile to check to make sure "config" has been
run (can't run config directly from the Makefile because it modifies the
Makefile;  thus make has to be run again after running config).

----------------- Released version 6.5, 12/17/92 ------------------
