How do I tell GNU Parallel to not quote the replacement string

Question

GNU Parallel quotes replacement strings by default so that they are not expanded by the shell. But in certain cases you really want the replacement string to be interpreted by the shell.

E.g.

$ cat variables.txt
--var1 0.1 --var2 0.2
--var1 0.11 --var3 0.03

Here I want GNU Parallel to run:

myprogram --var1 0.1 --var2 0.2
myprogram --var1 0.11 --var3 0.03

How is that done?

How is it done, if only some of the replacement strings should be interpreted:

E.g.

$ ls
My file1.txt
My file2.txt

And I want this run:

myprogram --var1 0.1 --var2 0.2 'My file1.txt'
myprogram --var1 0.11 --var3 0.03 'My file1.txt'
myprogram --var1 0.1 --var2 0.2 'My file2.txt'
myprogram --var1 0.11 --var3 0.03 'My file2.txt'

Answer 1

From version 20190722 you can use uq() in a perl replacement string to make that replacement unquoted:

parallel myprogram '{=1 uq(); =}' {2} :::: variables.txt ::: My*.txt

This can not be done in earlier versions. You can, however, unquote the full command with eval. This solves the first problem, but not the second.

parallel eval myprogram {} :::: variables.txt

If you prefer all replacement strings to be unquoted, you can do that by redefining them:

parallel --rpl '{} uq()' echo {} ::: '*'

You can put the --rpl in ~/.parallel/config to make them active by default (these are simply the definitions in the source code with uq() added):

--rpl '{} uq()'
--rpl '{#} 1 $_=$job->seq(); uq()'
--rpl '{%} 1 $_=$job->slot(); uq()'
--rpl '{/} s:.*/::; uq()'
--rpl '{//} $Global::use{"File::Basename"} ||= eval "use File::Basename; 1;"; $_ = dirname($_); uq()'
--rpl '{/.} s:.*/::; s:\.[^/.]*$::; uq; uq()'
--rpl '{/.} s:.*/::; s:\.[^/.]*$::; uq()'
--rpl '{.} s:\.[^/.]*$::; uq()'