Ubuntu – Use sed to replace the last space in each line with a comma, then remove all spaces

command linesedtext processing

I have a two-column, space delimited .txt file, but the first column has spaces (which are errors). I need to convert it to a csv, but I can't just replace all the spaces with commas.

Example input:

gi|118592783|ref|ZP_01550172.1|_biphenyl-2  3-diol_1    2-dioxygenase_[Stappia_aggregata_IAM_12614] 1

Desired output:

gi|118592783|ref|ZP_01550172.1|_biphenyl-23-diol_12-dioxygenase_[Stappia_aggregata_IAM_12614],1

How can I use sed (or anything else) to replace the last space in a row with a comma, then remove all remaining spaces? Would that effectively create a CSV file?

Best Answer

Something like:

sed -r 's/(.*) /\1,/; s/ //g'

The first substitution, being greedy, will cover all but the last space in the group, replacing the last with a ,. The second will then eliminate the rest.

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