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control default value of patsub_replacement from config-top.h; documentation updates

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Chet Ramey
2023-02-20 11:59:04 -05:00
parent 72c4a0f40d
commit 3b4d12c1a2
11 changed files with 1374 additions and 1268 deletions
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doc/bashref.texi
+19 -9
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@@ -2733,9 +2733,10 @@ word splitting.
The shell treats each character of @env{$IFS} as a delimiter, and splits
the results of the other expansions into words using these characters
as field terminators.
If @env{IFS} is unset, or its value is exactly @code{<space><tab><newline>},
the default, then sequences of
@code{ <space>}, @code{<tab>}, and @code{<newline>}
@code{space}, @code{tab}, and @code{newline}
at the beginning and end of the results of the previous
expansions are ignored, and any sequence of @env{IFS}
characters not at the beginning or end serves to delimit words.
@@ -2748,7 +2749,10 @@ Any character in @env{IFS} that is not @env{IFS}
whitespace, along with any adjacent @env{IFS}
whitespace characters, delimits a field. A sequence of @env{IFS}
whitespace characters is also treated as a delimiter.
If the value of @env{IFS} is null, no word splitting occurs.
If @env{IFS} is unset, word splitting behaves as if it contained
the default value @code{<space><tab><newline>}.
Explicit null arguments (@code{""} or @code{''}) are retained
and passed to commands as empty strings.
@@ -7614,14 +7618,19 @@ rules above.
@section Aliases
@cindex alias expansion
@dfn{Aliases} allow a string to be substituted for a word when it is used
as the first word of a simple command.
The shell maintains a list of aliases that may be set and unset with
the @code{alias} and @code{unalias} builtin commands.
@dfn{Aliases} allow a string to be substituted for a word that is in
a position in the input where it can be the first word of a simple
command. Aliases have names and corresponding values that are set
and unset using the @code{alias} and @code{unalias} builtin commands
(@pxref{Shell Builtin Commands}).
If the shell reads an unquoted word in the right position, it checks
the word to see if it matches an alias name. If it matches, the shell
replaces the word with the alias value, and reads that value as if it
had been read instead of the word.
The shell doesn't look at any characters following the word before
attempting alias substitution.
The first word of each simple command, if unquoted, is checked to see
if it has an alias.
If so, that word is replaced by the text of the alias.
The characters @samp{/}, @samp{$}, @samp{`}, @samp{=} and any of the
shell metacharacters or quoting characters listed above may not appear
in an alias name.
@@ -7633,6 +7642,7 @@ is not expanded a second time.
This means that one may alias @code{ls} to @code{"ls -F"},
for instance, and Bash does not try to recursively expand the
replacement text.
If the last character of the alias value is a
@code{blank}, then the next command word following the
alias is also checked for alias expansion.
@@ -7643,7 +7653,7 @@ command, and removed with the @code{unalias} command.
There is no mechanism for using arguments in the replacement text,
as in @code{csh}.
If arguments are needed, use a shell function
(@pxref{Shell Functions}).
(@pxref{Shell Functions}) instead.
Aliases are not expanded when the shell is not interactive,
unless the @code{expand_aliases} shell option is set using