TL;DR: awk and backslashes in the replacement argument of gsub is ugly.
With GNU Awk 4.0.2 we have:
$ echo '\' | awk '{ gsub("\\\\", "\\\\\\\\\\\\\\\\"); print }'
\\\\\\\\
and with GNU Awk 4.1.4 (and newer) we have:
$ echo '\' | awk '{ gsub("\\\\", "\\\\\\\\\\\\\\\\"); print }'
\\\\
This results in too much backslashes in /etc/issues for users of the
former version.
For the glory details I recommend reading through
https://www.gnu.org/software/gawk/manual/html_node/Gory-Details.html
https://bugs.debian.org/909147
As it's awkward to come up with an expression that does the same on both
versions (e.g. using --posix) use sed instead.
Signed-off-by: Uwe Kleine-König <u.kleine-koe...@pengutronix.de>
---
scripts/lib/ptxd_make_xpkg_pkg.sh | 14 +++++++-------
1 file changed, 7 insertions(+), 7 deletions(-)
diff --git a/scripts/lib/ptxd_make_xpkg_pkg.sh
b/scripts/lib/ptxd_make_xpkg_pkg.sh
index 5e69cefdc85d..685f4e549446 100644
--- a/scripts/lib/ptxd_make_xpkg_pkg.sh
+++ b/scripts/lib/ptxd_make_xpkg_pkg.sh
@@ -584,13 +584,13 @@ install replace figlet:
local escapemode="$2"
figlet -d "${PTXDIST_SYSROOT_HOST}/share/figlet" -- "${value}" | \
case "$escapemode" in
- # a lot of leaning toothpicks because we need to escape a literal
- # '\' with '\\' on multiple levels:
- # - one level for the string inside awk: \\\\\\\\\\\\\\\\ ->
\\\\\\\\
- # - one level for the shell string after sed -e: -> \\\\
- # - one level for the s expression inside sed: -> \\
- # - and finally, one level for /etc/issue: -> \
- etcissue) awk '{ gsub("\\\\", "\\\\\\\\\\\\\\\\"); print }' ;;
+ # /etc/issue needs each backslash quoted by another backslash. As
+ # the string is interpreted by the shell once more below, another
+ # level of quoting is needed such that every \ in the output of
+ # figlet needs to be replaced by \\\\. As a \ in sed needs to be
+ # quoted, too, this results in eight backslashes in the replacement
+ # string.
+ etcissue) sed 's,\\,\\\\\\\\,';;
*) ;;
esac | \
awk '{ if ($0 !~ "^ *$") printf("%s\\n", $0) }' # newlines for sed
--
2.19.0
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