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May 19, 2015 - A Look At The New Commandlinefu
I've put together a short writeup on what kind of newness you can expect from the next iteration of clfu. Check it out here.
March 2, 2015 - New Management
I'm Jon, I'll be maintaining and improving clfu. Thanks to David for building such a great resource!

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Psst. Open beta.

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Overcome Bash's expansion order

Terminal - Overcome Bash's expansion order
mkdir ${1..10}
2011-07-23 19:20:35
User: linuts
Functions: mkdir
Overcome Bash's expansion order

no need for seq or eval


There are 2 alternatives - vote for the best!

Terminal - Alternatives
eval "mkdir test{$(seq -s, 1 10)}"
2011-07-23 17:09:01
User: xakon
Functions: eval
Tags: bash seq eval

In order to create, let's say, 10 directories with a single process we can use the command:

mkdir test{1,2,3,4,5,6,7,8,9,10}

something extremely boring to type! Why not use seq?

seq -s, 1 10

and use its output inside the curly braces?

The obvious solution

mkdir test{$(seq -s, 1 10)}

is, unfortunately, too naive and doesn't work. The answer is the order of the shell expansions (feature of Bourne Shell, actually), where brace expansion happens before command substitution (according to Bash's manual).

The solution is to put another level of substitution, using the powerful and mystic command eval.

I found the trick in a similar problem in the post at http://stackoverflow.com/questions/6549037/bash-brace-expansion-in-scripts-not-working-due-to-unwanted-escaping

Know a better way?

If you can do better, submit your command here.

What others think

=$ mkdir ${1..10}

bash: ${1..10}: bad substitution

Comment by depesz 274 weeks and 1 day ago

The correct version of this would be

mkdir {1..10}

Comment by baerbl 273 weeks and 6 days ago

yeah, my shocker, shouldn't have the $ in there.

Comment by linuts 273 weeks and 6 days ago

Your point of view

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