tr - translating to ascii 31 (unit separator) -

i have csv file print in file replacing comma non printable ascii 31 unit separator. trying this:

 echo ${out} | tr ',' '\31' > ${in}

i use vim editor , know in vim should see ^_ if tr command successfull, unfortunatelly see ^y out there suggest solution?

the correct way is:

echo ${out} | tr ',' '\037' > ${in}

31 037 when converted octal

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