zcat shouldn't error out if you try to zcat an uncompressed file, it should just output the damned file !

There I said it !

32 comments

I agree. zgrep also works for uncompressed files, so we could use e.g. zgrep ^ instead of zcat.
- Thanks, didn't know that existed
  That's basically everything I was looking for !

Yeah, it's a pain. Leads to bad one liners:
for i in $(ls); do zcat $i || cat $i; done
- Btw, don't parse ls. Use find |while read -r instead.
  undefined
  
  find -maxdepth 1 -name "term" -print |while read -r file do zcat "$file" 2>/dev/null || cat "$file" done
  
  Won't this cause cat to iterate through all files in the cwd once zcat encounters an issue, instead of just the specific file?
  
  You can just do for f in * (or other shell glob), unless you need find's fancy search/filtering features.
  The shell glob isn't just simpler, but also more robust, because it works also when the filename contains a newline; find .. | while read -r will crap out on that. Also apparently you want while IFS= read -r because otherwise read might trim whitespace.
  If you want to avoid that problem with the newline and still use find, you can use find -exec or find -print0 .. | xargs -0, or find -print0 .. | while IFS= read -r -d ''. I think -print0 is not standard POSIX though.
- Thanks !
  But still we shouldn't have to resort to this !
  ~~Also, can't get the output through pipe~~
  for i in $(ls); do zcat $i || cat $i; done | grep mysearchterm
  ~~this appears to work~~
  ~~find . -type f -print0 | xargs -0 -I{} sh -c 'zcat "{}" 2>/dev/null || cat "{}"' | grep "mysearchterm"~~
  ~~Still, that was a speed bump that I guess everyone dealing with mass compressed log files has to figure out on the fly because zcat can't read uncompressed files ! argg !!!~~
  for i in $(ls); do zcat $i 2>/dev/null || cat $i; done | grep mysearchterm

How do you propose zcat tell the difference between an uncompressed file and a corrupted compressed file? Or are you saying if it doesn't recognize it as compressed, just dump the source file regardless? Because that could be annoying.
- Even a corrupt compressed files has a very different structure relative to plain text. "file" already has the code to detect exactly which.
  Still, failing on corrupted compression instead of failing on plaintext would be an improvement.
  
  What even is plain text anymore? If you mean ASCII, ok, but that leaves out a lot. Should it include a minimal utf-8 detector? Utf-16? The latest goofy encoding? Should zcat duplicate the functionality of file? Generally, unix-like commands do one thing, and do it well, combining multiple functions is frowned upon.

zgrep . * should do the trick
oh, there's also zcat -f *
- undefined
  
  -f --force If the input data is not in a format recognized by gzip, and if the option --stdout is also given, copy the input data without change to the standard output: let zcat behave as cat.
  I don't know why this isn't the top comment. I guess there might be some scenario where you'd want to know about non-gzip files where you don't expect them so changing the defaults would probably cause some subtle breakage. For shell use though, just an alias could be used; alias zcat=gzip -cdf
  
  in that case, i'd prefer a ~/bin/zcat with the contents
  undefined
  
  #!/bin/sh exec gzip -cdf "$@"
  this way, it's exec'able, unlike an alias or shell function.

I think that providing an exit status that is not 0 when zcat is used with an uncompressed file is useful. Though my opinion is less strong regarding whether it should write more text after an error occurred, it's probably more useful for a process to terminate quickly when an error occurred rather than risk a second error occurring and making troubleshooting harder.
I think that trying to change any existing documented features of widely used utilities will lead to us having less useful software in the future (our time is probably better spent making new programs and new documentation): https://www.jwz.org/doc/worse-is-better.html https://en.wikipedia.org/wiki/Worse_is_better
- Not improving existing software leads to stagnation.
  It's certainly a good part of why so much of linux is an awkward kludgy idiosyncratic mess to use.
  Whatever the first implementation does ends up being a suicide pact by default.
  Another option is to change cat to auto decompress compressed files, instead of printing gibberish.
  
  What operating system should I use with my laptop that isn't an awkward kludgy idiosyncratic mess? I would say that Windows has plenty of kludges, like having problems with certain file names. Many versions of macOS are UNIX® Certified Products (for example, macOS version 15.0 Sequoia on Intel-based Mac computers and on Apple silicon-based Mac computers), so it's surely not any less kludgy than Linux.
  I suppose that it's not bad to change documentation to be more specific, and change a program such that it matches the new documentation and wouldn't cause any harm if it replaced all the existing versions of the program, but makes it possible to use the program to solve more problems. That would be to "add functionality in a backward compatible manner".
  You are also free to create new programs that are not an exact replacement for existing programs, but can enable some people to stop using one or more other programs. That would not be what I describe as stagnation.
  "The cat utility shall read files in sequence and shall write their contents to the standard output in the same sequence.", so I would be very annoyed if it did something different with a certain file but not others. I wouldn't say that the contents of a file and the contents after the file is expanded are the same. In fact, I expect that some people use cat to process compressed files, and changing how cat acts with compressed files would probably cause them a large amount of annoyance, and would needlessly make a lot of existing documentation incorrect.
  
  Whatever the first implementation does ends up being a suicide pact by default.
  I agree. The behavior of rm and cat and cp and mv and dd and many other utilities don't necessarily have the interface I would prefer, but they are too widely used for it to be helpful to radically change them. It's somewhat unfortunate that these names are already reserved, but I don't think it's necessary to change them.
  In the same way, I don't have a problem with packages having generic names but not actually being useful: I've read that the requests and urllib3 packages for Python aren't being maintained very well, but I don't mind that as long as I can accomplish things while following best practices.
  Because of this, I'm not afraid to use names like "getRequest" or "result", especially if they were generated with an automatic refactoring, and I'm not upset when I see similarly generic names being used with source code I'm changing, since I know that the second name for something that's similar to an existing thing will have to actually be descriptive, but the first name is likely to not be.
  I have another example of how I'd apply these thoughts: the process for developing v2+ modules for the Go programming language strikes me as inelegant, so I would probably prefer to just create an entirely new repository rather than try to attempt that.

just use -f lol.
less $(which zcat) shows us a gzip wrapper. So we look through gzip options and see:
-f --force
Force compression or decompression. If the input data is not in a format recognized by gzip, and if the option --stdout is also given, copy the input data without change to the standard output: let zcat behave as cat.
- That works great now I can zcat -f /var/log/apache2/*

Celeste. Are you here? In a future search maybe?

Well, the source code is available. Fix it if you need it that bad.
- Man, I have a minor inconvenience.
  installs Gentoo
- Where is it? I can't seen to find it https://github.com/zCat?tab=repositories
  
  It's part of GNU Gzip, and zcat is basically just a shell script that runs exec gzip -cd "$@" meaning you can actually just do cat /usr/bin/zcat to get the source.

32 comments