Ensure a POSIX:2001 compliant 'echo' command.

1 files changed, 98 insertions, 1 deletions

diff --git a/gnulib-tool b/gnulib-tool
index 5a13973748..559aa7ca98 100755
--- a/gnulib-tool
+++ b/gnulib-tool
@@ -22,7 +22,7 @@
 
 progname=$0
 package=gnulib
-cvsdatestamp='$Date: 2007-06-22 18:16:40 $'
+cvsdatestamp='$Date: 2007-06-23 02:02:46 $'
 last_checkin_date=`echo "$cvsdatestamp" | sed -e 's,^\$[D]ate: ,,'`
 version=`echo "$last_checkin_date" | sed -e 's/ .*$//' -e 's,/,-,g'`
 nl='
@@ -410,6 +410,103 @@ func_ln_if_changed ()
   fi
 }
 
+# Ensure an 'echo' command that does not interpret backslashes.
+# Test cases:
+#   echo '\n' | wc -l                 prints 1 when OK, 2 when KO
+#   echo '\t' | grep t > /dev/null    has return code 0 when OK, 1 when KO
+# This problem is a weird heritage from SVR4. BSD got it right.
+# Nowadays the problem occurs in 4 situations:
+# - in bash, when the shell option xpg_echo is set,
+# - in zsh, when sh-emulation is not set,
+# - in ksh (e.g. AIX /bin/sh and Solaris /usr/xpg4/bin/sh are ksh instances,
+#           and HP-UX /bin/sh and IRIX /bin/sh behave similarly),
+# - in Solaris /bin/sh and OSF/1 /bin/sh.
+# We try the following workarounds:
+# - for all: respawn using $CONFIG_SHELL if that is set and works.
+# - for bash: unset the shell option xpg_echo.
+# - for zsh: turn sh-emulation on.
+# - for ksh: alias echo to a function that uses cat of a here document.
+# - for Solaris /bin/sh: respawn using /bin/ksh and rely on the ksh workaround.
+# - otherwise: respawn using /bin/sh and rely on the workarounds.
+# When respawning, we pass --no-reexec as first argument, so as to avoid
+# turning this script into a fork bomb in unlucky situations.
+have_echo=
+if echo '\t' | grep t > /dev/null; then
+  have_echo=yes # Lucky!
+fi
+# Try the workarounds.
+# Respawn using $CONFIG_SHELL if that is set and works.
+if test -z "$have_echo" \
+   && test "X$1" != "X--no-reexec" \
+   && test -n "$CONFIG_SHELL" \
+   && test -f "$CONFIG_SHELL" \
+   && $CONFIG_SHELL -c 'echo '\t' | grep t > /dev/null'; then
+  exec $CONFIG_SHELL "$0" --no-reexec "$@"
+  exit 127
+fi
+# For bash: unset the shell option xpg_echo.
+if test -z "$have_echo" \
+   && test -n "$BASH_VERSION" \
+   && (shopt -o xpg_echo; echo '\t' | grep t > /dev/null) 2>/dev/null; then
+  shopt -o xpg_echo
+  have_echo=yes
+fi
+# For zsh: turn sh-emulation on.
+if test -z "$have_echo" \
+   && test -n "$ZSH_VERSION" \
+   && (emulate sh) >/dev/null 2>&1; then
+  emulate sh
+fi
+# For ksh: alias echo to a function that uses cat of a here document.
+# The ksh manual page says:
+#   "Aliasing is performed when scripts are read, not while they are executed.
+#    Therefore, for an alias to take effect, the alias definition command has
+#    to be executed before the command which references the alias is read."
+# Because of this, we have to play strange tricks with have_echo, to ensure
+# that the top-level statement containing the test start after the 'alias'
+# command.
+if test -z "$have_echo"; then
+bsd_echo ()
+{
+cat <<EOF
+$*
+EOF
+}
+alias echo=bsd_echo 2>/dev/null
+fi
+if test -z "$have_echo" \
+   && echo '\t' | grep t > /dev/null; then
+  have_echo=yes
+fi
+if test -z "$have_echo"; then
+  unalias echo 2>/dev/null
+fi
+# For Solaris /bin/sh and OSF/1 /bin/sh: respawn using /bin/ksh.
+if test -z "$have_echo" \
+   && test "X$1" != "X--no-reexec" \
+   && test -f /bin/ksh; then
+  exec /bin/ksh "$0" --no-reexec "$@"
+  exit 127
+fi
+# Otherwise: respawn using /bin/sh.
+if test -z "$have_echo" \
+   && test "X$1" != "X--no-reexec" \
+   && test -f /bin/sh; then
+  exec /bin/sh "$0" --no-reexec "$@"
+  exit 127
+fi
+if test -z "$have_echo"; then
+  func_fatal_error "Shell does not support 'echo' correctly. Please install GNU bash and set the environment variable CONFIG_SHELL to point to it."
+fi
+if echo '\t' | grep t > /dev/null; then
+  : # Works fine now.
+else
+  func_fatal_error "Shell does not support 'echo' correctly. Workaround does not work. Please report this as a bug to bug-gnulib@gnu.org."
+fi
+if test "X$1" = "X--no-reexec"; then
+  shift
+fi
+
 # Command-line option processing.
 # Removes the OPTIONS from the arguments. Sets the variables:
 # - mode            list or import or create-testdir or create-megatestdir