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harald
Asked: 2011-12-20 04:07:11 +0800 CST

Safe way to determine size of a file using unix tools?

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I wonder, what's the best way to determine the size of a file using common unix tools. I need to determine the size of a file in bytes in a shell script. The problem is, that the shell script needs to be portable across different operating systems like osx, irix, linux -- that said: using the "stat" command may not work well, because the arguments required to get the result i want are different on almost every operating system.

I tried to use:

cat ... | wc -c

and while this seems to work quite well, i will probably get issues in a multibyte environment, won't i? So: what's a good way to do this?

linux mac-osx unix files

5 Answers

  1. For this purpose you can use the following:

    du --block-size=1 filename

    I have no idea about its portability. In command's man page it is listed to be in GNU coreutils package.

    If you want to determine the size of the file, rather than the space it takes on disk, add --apparent-size.

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  2. cksum FILE

    From wikipedia

    Interoperability

    The standard cksum command, as found on most UNIX-like OS (including GNU/Linux, *BSD, Mac OS X, and Solaris) uses a CRC algorithm based on the ethernet standard frame check and is therefore interoperable between implementations

    of course the interoperability is mentioned for the checksum and NOT for the counting bytes part.

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  3. stat -c %s /path/to/filename

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  4. ls and awk are pretty standard. You can try

    ls -l file | awk '{print $5}'
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  5. man wc

    Print newline, word, and byte counts

    user@machine:~$ ls -lh datefix.vim
-rw-r--r-- 1 user     group     264 2011-06-28 23:26 datefix.vim
user@machine:~$ wc datefix.vim
  6  12 264 datefix.vim
user@machine:~$ wc datefix.vim | awk '{print $3}'
264

    wc doesn't know or care about Unicode -- it thinks a byte is a byte. I also tested this out on a 234 MB .lzma file to proof it... so a simple wc -c will also get you what you want.

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