URL:
<http://savannah.gnu.org/bugs/?47171>
Summary: please fall back to system() when command is not
found on $PATH
Project: make
Submitted by: srivasta
Submitted on: Tue 16 Feb 2016 02:34:37 PM CST
Severity: 3 - Normal
Item Group: Enhancement
Status: None
Privacy: Public
Assigned to: None
Open/Closed: Open
Discussion Lock: Any
Component Version: None
Operating System: None
Fixed Release: None
Triage Status: None
_______________________________________________________
Details:
Hi,
This was reported by a debian user. Please retain a CC to
635646-forwar...@bugs.debian.org
so that the Debian BTS has a copy of your input.
Trying the following makefile:
test:
command -v ls
I get the following result:
$ make
command -v ls
make: command: Command not found
make: *** [test] Error 127
$ sh -c 'command -v ls'
/bin/ls
but POSIX sayeth
| An execution line is built from the command line by removing
| any prefix characters. Except as described under the at-sign
| prefix, the execution line shall be written to the standard
| output, optionally preceded by a <tab>. The execution line |
| shall then be executed by a shell as if it were passed as the
| argument to the system( ) interface, except that the shell −e
| option shall also be in effect.
The cause is that "make" expects to be run on a POSIX system, where
non-special shell builtins like "command" would be available for use by execvp
(see sh_cmds[] in job.c). See the explanation by Jilles Tjoelker at
http://bugs.debian.org/cgi-bin/bugreport.cgi?msg=43;bug=436466
for more details.
I can imagine two fixes, and both seem separately valuable:
a. one hand hand, introducing a new package to provide those
non-special builtins that are not provided by some
pseudo-essential package (using alternatives to deal with
alternative implementations where necessary):
#!/bin/sh
command -p ${0##*/} "$@"
b. on the other hand, teaching "make" to handle ENOENT from
execvp by falling back to the shell. (The shell can print a
message about it if that ENOENT was actually due to a
missing shared library or interpreter.) This way, "make"
could even use shell builtins that are not mandated by POSIX
when the system shell happens to implement them.
This report is about (b). Thoughts?
Manoj
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