Portable way to get file size in bytes in shell

Question

On Linux  I use stat --format   s  FILE  but Solaris I have access to doesn t have stat command  What should I use then   I m writing Bash scripts  and can t really install any new software on the system   I ve considered already using   perl -e   x stat shift  print  x 7   FILE   or even   ls -nl FILE   awk   print  5     But neither of these looks sensible - running Perl just to get file size  Or running 2 commands to do the same

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Finally I decided to use ls  and bash array expansion   TEMP      ls -ln FILE     SIZE   TEMP 4     it s not really nice  but at least it does only 1 fork execve  and it doesn t rely on secondary programming language  perl ruby python whatever

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BSDs have stat with different options from the GNU coreutils one  but similar capabilities   stat -f  z  lt file name gt     This works on macOS  tested on 10 12   FreeBSD  NetBSD and OpenBSD

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If you use find from GNU fileutils   size    find   -maxdepth 1 -type f -name filename -printf   s      Unfortunately  other implementations of find usually don t support -maxdepth  nor -printf  This is the case for e g  Solaris and macOS find

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Cross platform fastest solution  only uses single fork   for ls  doesn t attempt to count actual characters  doesn t spawn unneeded awk  perl  etc    Tested on MacOS  Linux - may require minor modification for Solaris     ln      ls -Lon   1        size     ln 3   echo  Size is     size bytes    If required  simplify ls arguments  and adjust offset in     ln 3       Note  will follow symlinks

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When processing ls -n output  as an alternative to ill-portable shell arrays  you can use the positional arguments  which form the only array and are the only local variables in standard shell  Wrap the overwrite of positional arguments in a function to preserve the original arguments to your script or function   getsize     set --   ls -dn   1    amp  amp  echo  5    getsize FILE   This splits the output of ln -dn according to current IFS environment variable settings  assigns it to positional arguments and echoes the fifth one  The -d ensures directories are handled properly and the -n assures that user and group names do not need to be resolved  unlike with -l  Also  user and group names containing whitespace could theoretically break the expected line structure  they are usually disallowed  but this possibility still makes the programmer stop and think

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if you have Perl on your Solaris  then use it  Otherwise  ls with awk is your next best bet  since you don t have stat or your find is not GNU find

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wc -c  lt  filename  short for word count  -c prints the byte count  is a portable  POSIX solution  Only the output format might not be uniform across platforms as some spaces may be prepended  which is the case for Solaris    Do not omit the input redirection  When the file is passed as an argument  the file name is printed after the byte count   I was worried it wouldn t work for binary files  but it works OK on both Linux and Solaris  You can try it with wc -c  lt   usr bin wc  Moreover  POSIX utilities are guaranteed to handle binary files  unless specified otherwise explicitly

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I ended up writing my own program  really small  to display just the size  More information here  http   fwhacking blogspot com 2011 03 bfsize-print-file-size-in-bytes-and html  The two most clean ways in my opinion with common Linux tools are     stat -c  s  usr bin stat 50000    wc -c  lt   usr bin wc 36912   But I just don t want to be typing parameters or pipe the output just to get a file size  so I m using my own bfsize

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Did you try du -ks   awk   print  1 1024    That might just work

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Even though du usually prints disk usage and not actual data size  GNU coreutils du can print file s  apparent size  in bytes   du -b FILE   But it won t work under BSD  Solaris  macOS

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You can use find command to get some set of files  here temp files are extracted   Then you can use du command to get the file size of each file in human readable form using -h switch      find  HOME -type f -name      -exec du -h         OUTPUT   4 0K     home turing Desktop JavaExmp TwoButtons java  4 0K     home turing Desktop JavaExmp MyDrawPanel java  4 0K     home turing Desktop JavaExmp Instream java  4 0K     home turing Desktop JavaExmp RandomDemo java  4 0K     home turing Desktop JavaExmp Buff java  4 0K     home turing Desktop JavaExmp SimpleGui2 java

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You first Perl example doesn t look unreasonable to me   It s for reasons like this that I migrated from writing shell scripts  in bash sh etc   to writing all but the most trivial scripts in Perl  I found that I was having to launch Perl for particular requirements  and as I did that more and more  I realised that writing the scripts in Perl was probably a more powerful  in terms of the language and the wide array of libraries available via CPAN  and more efficient way to achieve what I wanted   Note that other shell-scripting languages  e g  python ruby  will no doubt have similar facilities  and you may want to evaluate these for your purposes  I only discuss Perl since that s the language I use and am familiar with

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There is a trick in Solaris I have used  if you ask for the size of more than one file it returns just the total size with no names - so include an empty file like  dev null as the second file   eg     command fileyouwant  dev null  I can t rememebr which size command this works for ls wc etc - unfortunately I don t have a solaris box to test it

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on linux you can use du -h  FILE  does that work on solaris too

[linux] Portable way to get file size (in bytes) in shell?

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