6 ms·

And prefer redirection to cat. whatever < file.txt not cat file.txt | whatever Also, there is no need for - or z on GNU tar in t or x modes: t

And prefer redirection to cat. whatever < file.txt not cat file.txt | whatever Also, there is no need for - or z on GNU tar in t or x modes: tar tf whatever.tgz tar tf whatever.tar.bz2 tar tf whatever.txz ... tar xf whatever.tar.gz tar xf whatever.tar.Z ... all work just fine

TorKlingberg 9y ago
I know whatever < file.txt is slightly more efficient, but there is value is keeping things going left to right with pipes in between. It makes it easy to insert a grep or sort, or swap out a part.
- veddan 9y ago
  <file.txt grep foo | sort
  - joombaga 9y ago
    Oh cool. Didn't know this was possible.
  - BenjiWiebe 9y ago
    Ok, if that actually works, that's amazing. Wow.
    - vram22 9y ago
      It works because of the general principle that I mentioned here: https://news.ycombinator.com/item?id=15249370 https://news.ycombinator.com/item?id=15249370 The shell (not the command) is the one expanding those metacharacters, so (within limits), in: cmd < file or < file cmd where you put that piece (< file) on the line does not matter, because the actual command cmd never sees the redirection at all - it is done [1] by the time the command starts. The cmd command will only see the command line arguments (other than redirections) and options (arguments that start with a dash). Even expansion of $ and other sigils (unless quoted) happens before the command starts. [1] I.e. the shell and kernel set up the standard input of the command to be connected to the file opened for reading (in the case of < file).
traviscj 9y ago
I prefer cat because > vs < is an easy typo to make but one clobbers the file. Happy to pay the performance penalty as insurance against that.
- vram22 9y ago
  You can use the bash setting called noclobber to prevent such accidental deletion. https://en.wikipedia.org/wiki/Clobbering https://en.wikipedia.org/wiki/Clobbering

TorKlingberg 9y ago

I know whatever < file.txt is slightly more efficient, but there is value is keeping things going left to right with pipes in between. It makes it easy to insert a grep or sort, or swap out a part.

veddan 9y ago
<file.txt grep foo | sort
- joombaga 9y ago
  Oh cool. Didn't know this was possible.
- BenjiWiebe 9y ago
  Ok, if that actually works, that's amazing. Wow.
  - vram22 9y ago
    It works because of the general principle that I mentioned here: https://news.ycombinator.com/item?id=15249370 https://news.ycombinator.com/item?id=15249370 The shell (not the command) is the one expanding those metacharacters, so (within limits), in: cmd < file or < file cmd where you put that piece (< file) on the line does not matter, because the actual command cmd never sees the redirection at all - it is done [1] by the time the command starts. The cmd command will only see the command line arguments (other than redirections) and options (arguments that start with a dash). Even expansion of $ and other sigils (unless quoted) happens before the command starts. [1] I.e. the shell and kernel set up the standard input of the command to be connected to the file opened for reading (in the case of < file).

traviscj 9y ago

I prefer cat because > vs < is an easy typo to make but one clobbers the file. Happy to pay the performance penalty as insurance against that.

vram22 9y ago
You can use the bash setting called noclobber to prevent such accidental deletion. https://en.wikipedia.org/wiki/Clobbering https://en.wikipedia.org/wiki/Clobbering