bootstrap: take advantage of POSIX shell features

[gnulib.git] / ChangeLog

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+2012-05-13  Stefano Lattarini  <stefano.lattarini@gmail.com>
+
+       bootstrap: take advantage of POSIX shell features
+
+       The 'bootstrap' script offered by Gnulib script already uses POSIX
+       shell features (like $((...)) arithmetic expansions) that are not
+       supported by legacy Bourne shells like Solaris 10 /bin/sh.  This
+       means that bootstrap must already be run using a proper POSIX shell,
+       which will thus provide more features, like ${var#pattern} parameter
+       expansion or inversion of a command exit status with '!'.  We can
+       thus use these features to improve the clarity and the performances
+       of the bootstrap script.
+
+       Suggested by Eric Blake.
+
+       * build-aux/bootstrap: Prefer xpg4 parameter expansions over use
+       of sed/expr plus command substitutions, to save some forks.  While
+       we are at it, prefer the POSIX $(...) form of command substitution,
+       rather than the legacy form `...` (since the former is visually
+       clearer and interacts better with quoting), and prefer the idiom:
+         "if ! CMD; then ACTION ..."
+       over the idiom:
+         "if CMD; then :; else ACTION ..."
+       which was required by legacy Bourne shells not supporting '!'.
+
 2012-05-12  Bruno Haible  <bruno@clisp.org>
 
+       system-quote: Add more comments.
+       * lib/system-quote.h: Add more comments about wilcards and limitations.
+       Suggested by Eli Zaretskii <eliz@gnu.org>.
+
        sh-quote, system-quote: Add comments about wildcards.
        * lib/sh-quote.h: Clarify what happens with wildcard characters.
        * lib/system-quote.h: Likewise.