[SOLVED] maxSIZE of a file.

colucix · 05-26-2009, 06:31 AM

Quote:

Originally Posted by Sergei Steshenko

And for what an extra level of complexity with 'head -1' ? You will need one more sorting anyway.

Since ls -lS sorts files by size, head -1 returns the bigger one. That's it. Where do you see such a complexity?

Sergei Steshenko · 05-26-2009, 06:36 AM

Quote:

Originally Posted by colucix

Since ls -lS sorts files by size, head -1 returns the bigger one. That's it. Where do you see such a complexity?

When I copy-paste your command (searching from ~), without the 'cut' part, I get many lines, not just one line.

This is what 'man xargs' says in the beginning:

Code:

This manual page documents the GNU version of xargs.  xargs reads items from the standard input, delimited by blanks (which can be protected with double or single
       quotes or a backslash) or newlines, and executes the command (default is /bin/echo) one or more times with any initial-arguments followed by items read from stan-
       dard input.  Blank lines on the standard input are ignored.

- already invitation for trouble.

Sergei Steshenko · 05-26-2009, 07:14 AM

By the way,

Code:

stat --printf=%s FILE;echo ""

prints just file size.

colucix · 05-26-2009, 07:34 AM

Quote:

Originally Posted by Sergei Steshenko

When I copy-paste your command (searching from ~), without the 'cut' part, I get many lines, not just one line.

That's really odd. Whatever the output is, the head -1 should give just one line. It works on my system. Anyway, as usual, there are many ways to do the same task in linux.

Sergei Steshenko · 05-26-2009, 07:41 AM

Quote:

Originally Posted by colucix

That's really odd. Whatever the output is, the head -1 should give just one line. It works on my system. Anyway, as usual, there are many ways to do the same task in linux.

Try the command without 'head' in a filesystem with a lot of files and watch output - you'll see it doesn't do what it should - my point is:

Code:

find /usr -type f -print0 | xargs -0 ls -lS | head -10000 | less

yields, among other things, this (seen from inside 'less' with -N on):

Code:

   5894 -rw-r--r-- 1 root root        3 2007-09-26 16:31 /usr/lib/YaST2/trans/sv.status
   5895 -rw-r--r-- 1 root root        3 2007-09-26 16:31 /usr/lib/YaST2/trans/zu.status
   5896 -rw-r--r-- 1 root root 40073986 2009-03-27 19:57 /usr/lib/jvm/java-1.5.0-sun-1.5.0/jre/lib/rt.jar
   5897 -rwxr-xr-x 1 root root 12832612 2009-04-20 21:13 /usr/lib/xulrunner-1.9.0.9/libxul.so

, i.e. overall you do not the longest file on top, so 'head- 1' won't bring you the needed file.

Hitboxx · 05-26-2009, 07:42 AM

Hey, I got the output.

maxSIZE=`ls -lR $1 | grep '^-' | cut -c 32-45| sort -n | tail -1`

>The maximum size of the file in /home/jukeboxhero/Public/ is 1270 20 bytes

Changed the I to l in ls, removed the spaces in grep and replaced l with 1 in tail.

Thanks for all the help.

Sergei Steshenko · 05-26-2009, 07:46 AM

Quote:

Originally Posted by Hitboxx

Hey, I got the output.

maxSIZE=`ls -lR $1 | grep '^-' | cut -c 32-45| sort -n | tail -1`

>The maximum size of the file in /home/jukeboxhero/Public/ is 1270 20 bytes

Changed the I to l in ls, removed the spaces in grep and replaced l with 1 in tail.

Thanks for all the help.

'ls' is a bad idea, and "cut -c 32-45" is absolutely horrible and wrong.

And the output you gave us proves that you can't rely on character positions which you do in "cut -c 32-45".

So, generally speaking, you've got a wrong output.

But 'cut' does allow you to have the right output, and with 'stat' you wouldn't even need 'cut'.

Just look at your "1270 20 bytes" and tell us about the space.

colucix · 05-26-2009, 08:06 AM

Quote:

Originally Posted by Sergei Steshenko

, i.e. overall you do not the longest file on top, so 'head- 1' won't bring you the needed file.

You're right. This is because the standard input is buffered through the pipe, so xargs receive a certain number of file names at a time and execute the command. I stand corrected.