CODEWITHSUNDEEP
bashunixsnakemake
user7161770
user7161770

Reputation:

How to get pairs of brace expansions without getting all combinations?

I work on macOS High Sierra 10.13.3. My shell is bash.

When I type, echo {1,2}{3,4}

I get: 13 14 23 24.

Is there an option to get 13 24 only?

I am interested in creating many files where two locations in a file vary together. For example, I want the files:

file1file1 file2file2 file3file3

It would be convenient to write something like file{1,2,3}file{1,2,3} option instead of file1file1 file2file2 file3file3.

I would like to be able to use this expansion in a command, such as:

touch file{1,2,3}file{1,2,3} option to create three files.

I hope that the functionality I am looking for is clear.

Clarification

Ultimately, the context I want to use this functionality in is with a snakemake command:

snakemake --cores 3 release{42,43,44}/file{42,43,44}.txt

where I want snakemake to produce the files release42/file42.txt, release43/file43.txt and release44/file44.txt.

If I use a loop to achieve this, the files will be produced in succession. However, by typing snakemake release42/file42.txt release43/file43.txt release44/file44.txt, the three files will be produced simultaneously. However, as I am lazy, I want to type something shorter than snakemake release42/file42.txt release43/file43.txt release44/file44.txt.

Upvotes: 4

Views: 156

Answers (2)

karakfa
karakfa

Reputation: 67527

to get 13 14 do 

$ echo 1{3,4}

for the duplicates, there are other ways

$ for i in {1..3}; do printf "file%dfile%d " $i $i; done
file1file1 file2file2 file3file3

to use with touch

$ for i in {1..3}; do touch "file${i}file${i}"; done

or, using all filenames at once

$ touch $(for i in {1..3}; do printf "file%dfile%d " $i $i; done)

Upvotes: 1

Charles Duffy
Charles Duffy

Reputation: 295679

Use a loop to form an array.

items=( )
for i in {42,43,44}; do
  items+=( "release$i/file$i.txt" )
done

snakemake "${items[@]}"

This runs snakemake only once, with all the files listed.

Upvotes: 2

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