I am using the terminal inside emacs to modify and clean textfiles (colon separated) for import into MySQL – mostly with SED, GREP, AWK.
Replacing TAB in a textfile with SED was not as straightforward as I thought. So Google came up with an excellent post on macworld.com and here especially one post suggesting perl as a solution. It turned out perl behaves inside the pipe the same way as SED/AWK.
Replacing TAB ‘\t‘ with colon ‘,‘ in a textfile ‘SomeFile.txt‘ can be done with:
perl -pi -e 's/\t/,/g' SomeFile.txt
or using the pipe, which can be combined with grep, sed, awk, tr, head, tail, etc…
cat SomeFile.txt | perl -pi -e 's/\t/,/g'
*Very* similar to the sed invocation, except for the flags. “-pi” for “*print* every line out after making the changes, while editing *inplace*. That is, no backup file is kept. In reality, a temp file is written, and if all is well (ie the operation succeeds), the temp file is shifted “onto” the original file, giving the appearance of an in-place edit.