autoconf: Invoking the Shell

1 
1 11.2 Invoking the Shell
1 =======================
1 
1 The Korn shell (up to at least version M-12/28/93d) has a bug when
1 invoked on a file whose name does not contain a slash.  It first
1 searches for the file's name in `PATH', and if found it executes that
1 rather than the original file.  For example, assuming there is a binary
1 executable `/usr/bin/script' in your `PATH', the last command in the
1 following example fails because the Korn shell finds `/usr/bin/script'
1 and refuses to execute it as a shell script:
1 
1      $ touch xxyzzyz script
1      $ ksh xxyzzyz
1      $ ksh ./script
1      $ ksh script
1      ksh: script: cannot execute
1 
1    Bash 2.03 has a bug when invoked with the `-c' option: if the
1 option-argument ends in backslash-newline, Bash incorrectly reports a
1 syntax error.  The problem does not occur if a character follows the
1 backslash:
1 
1      $ $ bash -c 'echo foo \
1      > '
1      bash: -c: line 2: syntax error: unexpected end of file
1      $ bash -c 'echo foo \
1      >  '
1      foo
1 
1 ⇒Backslash-Newline-Empty, for how this can cause problems in
1 makefiles.
1