build: fix incorrect use of shell commands in handmade libtool file #258
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The "echo" command was soft-deprecated from the shell programming language in ~1992. There is no way to use it correctly if: - the "-e" or "-n" or "-E" or any other options are used - backslash escape sequences are used - the printed string contains shell variables containing either of the above In recognition of the fact that echo was historically used in many scripts, some of which avoided these issues and therefore succeeded when run, the "echo" command was NOT marked as obsolescent, out of fear that marking it as obsolescent would lead to vendors removing "echo" entirely and breaking existing scripts (or at least, the subset of scripts which managed to work correctly). However, it is warned against, that after 1992 you should avoid writing new code that uses "echo" and instead use "printf". printf has an actual definition of its behavior, which echo did not, and that behavior is to interpret backslash escapes in the first parameter, which is necessary by this Makefile.am in order to embed newlines into the generated libtool file. Simply replacing "echo -e" with "printf" will therefore correctly and reliably do the intended functionality. We also add one final embedded newline to avoid producing a file without an end-of-line character on the last line of the file. Fixes: ckolivas#257 Signed-off-by: Eli Schwartz <[email protected]>
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The "echo" command was soft-deprecated from the shell programming language in ~1992. There is no way to use it correctly if:
In recognition of the fact that echo was historically used in many scripts, some of which avoided these issues and therefore succeeded when run, the "echo" command was NOT marked as obsolescent, out of fear that marking it as obsolescent would lead to vendors removing "echo" entirely and breaking existing scripts (or at least, the subset of scripts which managed to work correctly).
However, it is warned against, that after 1992 you should avoid writing new code that uses "echo" and instead use "printf".
printf has an actual definition of its behavior, which echo did not, and that behavior is to interpret backslash escapes in the first parameter, which is necessary by this Makefile.am in order to embed newlines into the generated libtool file. Simply replacing "echo -e" with "printf" will therefore correctly and reliably do the intended functionality. We also add one final embedded newline to avoid producing a file without an end-of-line character on the last line of the file.
Fixes: #257