At a very high level, greedy matching attempts to find the last or longest possible match, and lazy matching attempts to find the first possible match and stops there. Now having established some foundational knowledge about how grep searches can work, we will drop the knowledge bomb — the exact same grep expression on Linux using GNU grep may produce completely different or no results on Mac using BSD grep , especially when using these different types of matching.
The first time I found this out I spent an inordinate and unnecessary amount of time banging my head against a wall typing and re-typing the same expression across systems but seeing different results. Rather, I will get straight to the point of what you need to know and consider when using this utility across systems to perform effective searches. First, how do we even specify a lazy search? Here the fun begins. We did the exact same command on both systems and it returned different results. No changes necessary there. Ever performed a grep search and got a ton of very imprecise and unnecessarily large though technically correct results?
This implementation difference and issue could certainly have been the cause.
Install coreutils on Mac OSX
If only you knew then what you know now…. The following shows some examples:. There you have it. Hopefully you are now a bit more informed not only about the differences between Lazy and Greedy matching, but also about the difference in requirements across systems. However, not all strings are created equal. Very useful. Do not ask why.
I highly encourage you to avoid the rabbit hole of lacking logic that I endured when I first found this out. Of all the pandas, this is a very sad one. So, how can I possibly use GNU strings on it?
Well, my friends, at the end of this post I will revisit exactly how this can be achieved using a nearly irreplaceable third-party package manager. Now, go back and re-run the above tools against various files and binaries from your previous investigations you performed from the Mac command line.
Though there are many uses for it, I tend to use it mostly for substitutions, deletion, and permutation switching the order of certain things , which can be incredibly useful for log files with a bunch of text. This statement also utilizes sed variables, the understanding of which I will leave to the reader to explore.
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Believe it or not, there are actually two common problems here. Below are a few options that will work around this issue and there are more clever ways to do it as well. Use the literal i. Unfortunately, this only solves the first of two problems, the second being that BSD sed still does not allow for lazy matching from my testing, though I am possibly just missing something. So, even if you use 1 or 2 above, it will only match the last found pattern and not all the patterns we need it to.
Well, I leave that up to your judgment. Sometimes yes, sometimes no.
High Performance Computing for Mac OS X
This script will install coreutils, bash, git and more updated tools. To leave a comment for the author, please follow the link and comment on their blog: R news and tutorials contributed by R bloggers. Home About RSS add your blog! Here you will find daily news and tutorials about R , contributed by over bloggers. There are many ways to follow us - By e-mail: On Facebook: If you are an R blogger yourself you are invited to add your own R content feed to this site Non-English R bloggers should add themselves- here.
Install GNU and non-GNU Tools via Homebrew
When I run the first command to install homebrew it shows the messages below. The security changes that the script wants to implement make me nervous. Could you post an issue here: Another reason that Apple bundles many outdated GNU software bash, gdb, etc. Which is a bit of a pathetic move from GPL.
Blocking every OS X user from using a few great tools out of spite for Apple not being open source. This is absurd. Get your facts straight before insulting others. Nice twist of the reality, man. Did you notice anything different? Dear Hong, thank you so much for this post!
Related gnu tools for mac os x
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