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bash and dash evaluate variables differently.
dash will evaluate '\\' every time it is read whereas bash does not.
TEST_STRING="$TEST_STRING \\$i"
echo $TEST_STRING
With i=123
On bash, that will print "\123"
but on dash, that will print the escape sequence of \123 as the \ will be
interpreted again in the echo.
The dynevent_limitations.tc test created a very large list of arguments to
test the maximum number of arguments to pass to the dynamic events file.
It had a loop of:
TEST_STRING=$1
# Acceptable
for i in `seq 1 $MAX_ARGS`; do
TEST_STRING="$TEST_STRING \\$i"
done
echo "$TEST_STRING" >> dynamic_events
This worked fine on bash, but when run on dash it failed.
This was due to dash interpreting the "\\$i" twice. Once when it was
assigned to TEST_STRING and a second time with the echo $TEST_STRING.
bash does not process the backslash more than the first time.
To solve this, assign a double backslash to a variable "bs" and then echo
it to "ts". If "ts" changes, it is dash, if not, it is bash. Then update
"bs" accordingly, and use that to assign TEST_STRING.
Now this could possibly just check if "$BASH" is defined or not, but this
is testing if the issue exists and not just which shell is being used.
Link: https://lore.kernel.org/r/20250414210900.4de5e8b9@gandalf.local.home
Fixes: 581a7b26ab ("selftests/ftrace: Add dynamic events argument limitation test case")
Reported-by: Mark Brown <broonie@kernel.org>
Closes: https://lore.kernel.org/all/350786cc-9e40-4396-ab95-4f10d69122fb@sirena.org.uk/
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Acked-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the reStructuredText markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.