Hacker News Reader

Hacker News

Comment by rootsudo | Hacker News Reader

Parent Full thread

rootsudo

I did not know I could do {001...999} with wget! wow!

View on HN

That's a shell feature, not wget's.

Really? I thought the shell could only expand globs if it matches files on the local file system?

Thoae aren't globs, if you put an asterisk there it would not work.

You're right regarding glob functionality, but the curly braces are a separate shell feature. The most useful idiom I use it for is renaming or copying, e.g.:

cp filename{,_backup}

The feature is called brace expansion:

https://www.gnu.org/software/bash/manual/html_node/Brace-Exp...

You may also be interested in yet another powerful feature that is parameter expansion:

https://www.gnu.org/software/bash/manual/html_node/Shell-Par...

Filename expansion (nitpick: often mistaken for globbing) is performed last:

https://www.gnu.org/software/bash/manual/html_node/Filename-...

> nitpick: often mistaken for globbing

What exactly would you call globbing if not the feature that is controlled using the nullglob, failglob, nocaseglob and dotglob options as well as the GLOBIGNORE variable.

Globbing has an ambivalent definition given that it’s mostly used for filename matches (especially given its origin as the glob command), but it’s really a specific form of pattern matching using wildcards such as * and ?, it need not apply only to filenames or paths on the filesystem: this matching is also used to match strings in case/in/esac constructs and test’s == !=

https://www.gnu.org/software/bash/manual/bash.html#Condition...

I guess one could say globbing is applying this pattern matching to filter a list.

Curl has it built in:

    curl -O 'https://example.org/[2-4].jpg'

(quotes disable any kind of shell expansion)

Of course, this only works well with non-ancient bash, not the ancient version which ships with MacOS, which will do {1.999} but can't do the leading zeros (you can use printf '%.3d' as a separate step).

brew is your friend here, it has the latest version. Works well.

Afaik macos ships with zsh now, which supports that feature.

It isn't bound by command. You can use it everywhere!

You mean, you didn't know that wget can be given more than one URL argument it can fetch, and that Bash can generate arguments with interpolated numbers using {from...to}.

Reply on news.ycombinator.com