Why?

Concatenation (.) forces scalar context. Arrays in scalar context return their size.

How?

You can either use join: 
$tmp = "paste -d';' " . join(' ', @{ $csvheader{x_} }) . ' > all.x.txt
+';

[download]

or just double quote the array, its members will be separated by $" which is a space by default: 

$tmp = "paste -d';' @{ $csvheader{x_} } > all.x.txt";

[download]

Alternative

Instead of using paste, use Text::CSV_XS to process your CSV files. It handles quoted fields, escaped separators and quotes, and more.

($q=q:Sq=~/;[c](.)(.)/;chr(-||-|5+lengthSq)`"S|oS2"`map{chr |+ord
}map{substrSq`S_+|`|}3E|-|`7**2-3:)=~y+S|`+$1,++print+eval$q,q,a,

[download]

In reply to Re: how to get out data of a hash? by choroba
in thread how to get out data of a hash? by blaui

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