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Show HN: A simple Unix cat implementation in various languages

• rspivak 7y ago
  Feel free to add your own implementation. :)
  • eesmith 7y ago
    FWIW, iter() handles the logic of testing for an explicit EOF marker, so another way to write it is: import sys with open(sys.argv[1]) as fin: for c in iter((lambda: fin.read(1)), ""): sys.stdout.write(c)
    • rspivak 7y ago
      That's a good point. Thanks!
• zzo38computer 7y ago
  Here is another implementation using Node.js (although it does not explicitly check for EOF): require("fs").createReadStream(process.argv[2]).pipe(process.stdout) Here is a implementation in PostScript (it does explicitly check for EOF, and specifically deals with one byte at a time): /o (%stdout) (w) file def ARGUMENTS 0 get (r) file { dup read { o exch write } { quit } ifelse } bind loop (I have no GitHub account. But if the owner of that repository want to add, they can add what I have; I post this message (and all of my other messages on Hacker News) to public domain.)
  • rspivak 7y ago
    Thank you for the implementations! Do you have any suggestions how to test the postscript code on mac/linux? I tried on macos using ghostscript, but I get the following error: $ gs cat.ps helloworld.txt Error: /undefined in ARGUMENTS ... Thanks!
    • zzo38computer 7y ago
      To give command-line arguments to a PostScript program in Ghostscript, you must prefix the name of the PostScript file with two minus signs, such as: gs -dNODISPLAY -q -- cat.ps helloworld.txt (The -dNODISPLAY and -q are not needed to get this PostScript program to work, but -dNODISPLAY disables graphical output, and -q avoids Ghostscript's messages getting mixed in with the PostScript program's output. You might also need -dNOSAFER; if you get a invalidaccess error, try that. As far as I know, ARGUMENTS and -- are a feature specific to Ghostscript.)