In the linux shell, the following command will recursively search and replace all instances of \'this\' with \'that\' (I don\'t have a Linux shell in front of me, but it sho
OS X uses a mix of BSD and GNU tools, so best always check the documentation (although I had it that less didn't even conform to the OS X manpage):
https://web.archive.org/web/20170808213955/https://developer.apple.com/legacy/library/documentation/Darwin/Reference/ManPages/man1/sed.1.html
sed takes the argument after -i as the extension for backups. Provide an empty string (-i '') for no backups.
The following should do:
LC_ALL=C find . -type f -name '*.txt' -exec sed -i '' s/this/that/ {} +
The -type f is just good practice; sed will complain if you give it a directory or so.
-exec is preferred over xargs; you needn't bother with -print0 or anything.
The {} + at the end means that find will append all results as arguments to one instance of the called command, instead of re-running it for each result. (One exception is when the maximal number of command-line arguments allowed by the OS is breached; in that case find will run more than one instance.)