cmd/go: print shell commands safely

[robpike]

The printing of commands by the go tool is simple-minded, can be incorrect in the face
of empty strings and other issues, ignores system-dependent issues ($foo vs %foo;
quoting, etc.) and should be improved. The current setup just calls Printf or special
formatting routines that sometimes (not always) expand variables, and ignore local
quoting and other conventions (rm vs. del for example). It's not important but it is
worth doing right.

It's a big job.

[robpike]

Comment 1:

Issue #5274 has been merged into this issue.

[gopherbot]

Comment 2 by toqueteos:

I'm sorry Rob I forgot to search for "shell".
Is the idea of a replay command suitable or it's better to ouput native shell commands?

[alexbrainman]

Comment 3:

To sumup from https://golang.org/issue/5274. Possible unix to
windows command translation candidates:
"cp" -> "copy /y" 
"mkdir -p" -> "mkdir"
"rm -f" -> "del /f /q" for files and "rmdir /s /q" for directories
"rm -r" -> same as before
Alex

[alexbrainman]

Comment 4:

Issue #5274 has been merged into this issue.

[rsc]

Comment 5:

I am not sure it is worth doing right.
The printing of commands by the go tool is meant to be informational, not a working
shell script.

[alexbrainman]

Comment 6:

I am with rsc on this. I suspect correct windows translation could be complicated (too
many unusual parameters options) or impossible to do correctly. I think clarity is most
important here.
Alex

[rsc]

Comment 7:

Labels changed: added go1.3maybe.

[rsc]

Comment 8:

Labels changed: added release-none, removed go1.3maybe.

[rsc]

Comment 9:

Labels changed: added repo-main.

[bcmills]

The printing of commands by the go tool is meant to be informational, not a working shell script.

As of CL 55350 (for #21427), we do have a test that the output of at least a very basic go build -x is a working shell script.