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Dollar-paren expansion beats backticks for being nestable.

E.g.: I like dumping temporary files with timestamps:

some-command-to-generate-log > /tmp/log-$( date +%Y%m%d-%H%M%S )

Now, if I want to wrap that in a larger loop -- say, iterating over a number of files or parameters:

command $( expansion one $( expansion 2 ))

Works

With backticks you'd have to do escapes:

command `expansion 1 \`expansion 2\` `

... which gets tedious.



I like to use (for GNU date at least): $ date -Iseconds 2011-11-21T10:56:17+0000

because it requires less typing. The ISO 8601 standard format.

-Is, -Im, -Ih, and -Id allow you to change the displayed resolution.

Bizarrely, this doesn't seem to be documented in my version of date (coreutils 8.10).


A lot of the date documentation is unfortunately in info only. Debian (and derived distros) do a good job of updating the manpages.

That said, I can't find "-I" documented anywhere.

What I like about the timestamp I use is that it's semantic but sorts lexically as well. Though yours does as well. Hrm.




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