suppress progress status in esgfetchtables when output is not to a terminal

[alaniwi]

When esgfetchtables output is redirected to a file, the file contains a mess such as:

^MFetching cmip6 tables from 01.00.30 reference: 2% | 1/48 files^MFetching cmip6 tables from 01.00.30 reference: 4% | 2/48 files^MFetching cmip6 tables from 01.00.30 reference: 6% 

(etc...)

It would be better to clean that up by suppressing this and instead just report (for each branch) one line indicating the total files, after fetching is complete. For example:

Fetched cmip6 tables from 01.00.30 reference: 48 files

Behaviour to be controlled by sys.stdout.isatty().

[glevava]

How did you redirect the output of the esgfetchtables?
I have no problem here:

$> esgfetchtables -p cmip6 --branch 01.00.30 --tables-dir . > log.out
$> cat log.out 
Fetching cmip6 tables from 01.00.30 reference: 100% | 48/48 files

It seems to be terminal-dependent.
Did you try using the native --log flag instead?

[alaniwi]

What do you see if you inspect your log.out using less or some other tool? I am wondering whether your output file contains multiple lines separated by carriage-return characters, but when using cat to a terminal this is not evident.

I didn't try --log. I guess that it can be used, but this doesn't allow the user to choose the filename, or to write to a pipe.

[glevava]

Actually, using less or vi makes the ^M appearing.
Due to the progress bar, esgprep could be incompatible with unix pipe chain.
If you only need a log of the command-line, I can think about the --log flag to let you set the log name.

[glevava]

This issue is related to the untested pull request and part of the next release. To be close when release cut.