UNIX for Beginners Questions & Answers

Hello and thanks in advance for any help anyone can offer me

I'm trying to learn the find command and thought I was understanding it... Apparently I was wrong. I was doing compound searches and I started getting weird results with the -size test. I was trying to do a search on a 1G file owned by the user database. I was expecting to get a single file back, but for some reason the find returns not only the 1G file but the scripting files owned by the database user. I've been messing with this for a while trying to understand it. I can filter it out by using a -not -name ".*" but that's not the point. I want to understand why it's including the start up scripts & what I'm doing wrong. Here's the command and the results... If someone could tell me what I'm doing wrong I would greatly appreciate it!!!

Code:

find /home -type f -user database -size 1G -ls
13774125 4 -rw-r--r-- 1 database database 18 Nov 20 2015 /home/database/.bash_logout
13774135 4 -rw-r--r-- 1 database database 193 Nov 20 2015 /home/database/.bash_profile
13774136 4 -rw-r--r-- 1 database database 231 Nov 20 2015 /home/database/.bashrc
13774141 1048576 -rw-r--r-- 1 database root 1073741824 Feb 16 11:10 /home/database/large1.log

Moderator's Comments:

Please use CODE tags as required by forum rules!

Not so weird if you read the man page meticulously. man find:

Hi RudiC,
I don't understand your comments on this issue. The command in this case is:

Code:

find /home -type f -user database -size 1G -ls

which is looking for regular files owned by user database that contain exactly 1073741824 bytes. I don't see that any of first three lines of the -ls output provided by the above find command meet that criteria.

I agree that if the command had been:

Code:

find /home -type f -user database -size -1G -ls

then the output shown might be expected. But with 1G as the -size primary's argument (not -1G), I don't understand the output shown.

I don't think so: because the size (which is a small fraction of a GB) is rounded up to the next unit (GB here, therefore 1GB) all files with 1GB and less (but at least 1c) are shown.

I hope this helps.

bakunin

Thanks for the reply!

The fact the 1st three lines appear (Bash startup scripts) but don't meet the criteria of my find command when I explicitly using the -size 1G test is why I'm posting. I would expect with the find criteria I'm using for ONLY the large1.log to show up. I'm trying to figure out why the Bash startup scripts are appearing when they shouldn't be.

Hi bakunin,
No. When no units are specified, such as with -size 2, it is looking for a file that has a size that fits in 2 512-byte blocks which corresponds to a file with a file size that is 513 through 1024 bytes. But when units are specified, an unsigned number is looking for a file with the exact size specified (at least with a BSD-based find utility which is also used on macOS systems). Note that the POSIX standard's find utility's -size primary does not include a units modifier except c (which specifies that the number is counting bytes instead of 512-byte blocks); it just has negative numbers (meaning less than number), unsigned numbers (meaning exactly that number), and positive numbers (with a leading + meaning more than number).

If some other system's find utility treats unit modifiers as block size multipliers instead of just numbers of bytes, that difference in behavior from BSD might be a reason why POSIX hasn't standardized modifiers other than c.

Hi bodisha,
What operating system are you using?

Hi bodisha,
Guessing that the find that you're using behaves differently than the macOS/BSD find utility I'm using and that you really do only want to select files that are exactly of size 1G bytes, try:

Code:

find /home -type f -user database -size 1073741824c -ls

If you're looking for files that are at least 1G bytes, try:

Code:

find /home -type f -user database -size +1073741823c -ls