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

On Linux, I use stat --format="%s" FILE, but the Solaris machine I have access to doesn't have the 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 two programs to do the same?

Solution 1:

wc -c < 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 < /usr/bin/wc. Moreover, POSIX utilities are guaranteed to handle binary files, unless specified otherwise explicitly.

Solution 2:

I ended up writing my own program (really small) to display just the size. More information is in bfsize - print file size in bytes (and just that).

The two cleanest ways in my opinion with common Linux tools are:

stat -c %s /usr/bin/stat

50000


wc -c < /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.

Solution 3:

Even though du usually prints disk usage and not actual data size, the GNU Core Utilities du can print a file's "apparent size" in bytes:

du -b FILE

But it won't work under BSD, Solaris, macOS, etc.

Solution 4:

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 one fork+execve, and it doesn't rely on a secondary programming language (Perl, Ruby, Python, or whatever).