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Sometimes you have a bunch of .csv files, but you’d like to have one big .csv file. You can merge them in Excel, Google Sheets, or something similar, but that’s slow and error-prone. Plus, you might be dealing with something like a zip code — which starts with a zero — which is annoying to deal with in Excel.

So what’s a better solution?

The command line approach to doing this in Mac OS X and a compatible Linux/BSD system looks like this:

cat *.csv >mergedFile.csv

If that’s self-explanatory then you’re done. Enjoy.

What’s Happening Here?

The “cat” command is short for concatenate, or basically combine. The usage structure looks like this:

cat [options] [filenames] [-] [filenames]

That cat command is really good for reading files. You’d type in: cat fileName

cat works with output redirection via the greater than sign: >.

cat fileName0 > fileName1 will copy the contents of file 0 to file 1.

cat is more obviously used for concatenation. This would happen in a scenario like: cat fileName0 fileName1, which would combine the two files into the text on the screen, but not edit the files or create a file.

cat fileName0 fileName1 > fileName2 will get file 0 and file 1 and combine them in the newly created file 2.

So what about our command?

cat *.csv >mergedFile.csv will combine all the csv files in a directory and place them in a newly created file, known as mergedFile.csv.

September 7th, 2019

Posted In: Localhost / Environment

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