Using sed on Mac OS 10 to replace tab character in text files

Question

I've been searching here for quite some time, and though I have found some really good info, nothing quite zeros in on my issue. Short-n-sweet, I'm using sed on Mac OS 10.11 to try and replace the tab character with the pipe character. All the info I have found on this so far, the syntax may work on other platforms but not on Mac OS 10.11. I know sed works on 10.11 as I can replace normal, standard characters all day long and even some punctuation like a comma. And yes, I have tried using \t. The sed string I found that works with standard characters is the following:

sed -i '' -e 's/,/|/g' /Users/username/Desktop/TABs2PIPE.txt

When I use \t in place of the , in the above string, it simply replaces all the lowercase t in the file.

So, any other Macheads out there who have gotten this to work I really would appreciate some help, thanks in advance.

Answer 1

OSX sed is BSD-derived; this lineage of sed has never accepted \t as notation for the TAB character, IIRC. If your shell is bash (which is the default on OSX), try this instead:

sed -i '' -e $'s/\t/|/g' file_to_process.txt

$'...' is a bash extension; it's a '...' quoted word, but C-style backslash escapes are interpreted within. From the bash manpage:

Words of the form $'string' are treated specially. The word expands to string, with backslash-escaped characters replaced as specified by the ANSI C standard.

So, sed will see -e s/ /|/g where the gap between the first two spaces is a literal TAB character, and it should do the Right Thing with that.

If your shell is not bash, you can probably type a literal tab character yourself by typing control-V and then TAB.

Answer 2

The way sed handles backslash-T is certainly unexpected if you haven't encountered it before!

This works:

sed -i s/\<CTRL-V><TAB>/\|/g text.txt

Where <CTRL-V> and <TAB> are the actual keys pressed.