[SOLVED] linux find command fail with four '-name'

MrUmunhum · 10-29-2014, 07:32 PM

Hi group.
I found an interesting problem using the find command. If I use '-or -name' with than 3 '-name' options the command fails. Here is the output of a three parm and 4 parm example.

Quote:

find ../.. -name '*.log' -or -name 'core.*' -or -name '*~' -exec ls -l {} \;
-rwxr-xr-x. 1 wre00 root 107 Dec 26 2011 ../../Makefile.am~
-rw-r--r--. 1 wre00 root 21077 Oct 29 15:25 ../../Makefile~
find ../.. -name '*.log' -or -name 'core.*' -or -name '*~' -or -name '*.dat' -exec ls -l {} \;

I am running Fedora 13. Care to comment?

rknichols · 10-29-2014, 07:46 PM

Quote:

Originally Posted by MrUmunhum

Code:

find ../.. -name '*.log' -or -name 'core.*' -or -name '*~' -exec ls -l {} \;

Please use [CODE]...[/CODE] tags and not [QUOTE] tags for code. Material that is already a quote will not be automatically quoted in a followup.

The way you have it written, the "-exec" action is bound only to the last "-name" test, i.e., the implied parentheses are:

Code:

find ../.. -name '*.log' -or -name 'core.*' -or \( -name '*~' -exec ls -l {} \; \)

You need explicit parentheses around the set of "-name" tests:

Code:

find ../.. \( -name '*.log' -or -name 'core.*' -or -name '*~' \) -exec ls -l {} \;

astrogeek · 10-29-2014, 07:48 PM

What rnichols said...

MrUmunhum · 11-02-2014, 04:45 PM

Quote:

Originally Posted by rknichols

Please use [CODE]...[/CODE] tags and not [QUOTE] tags for code. Material that is already a quote will not be automatically quoted in a followup.

Fair enough, my fault.

Quote:

Originally Posted by rknichols

The way you have it written, the "-exec" action is bound only to the last "-name" test, i.e., the implied parentheses are:

Code:

find ../.. -name '*.log' -or -name 'core.*' -or \( -name '*~' -exec ls -l {} \; \)

You need explicit parentheses around the set of "-name" tests:

Code:

find ../.. \( -name '*.log' -or -name 'core.*' -or -name '*~' \) -exec ls -l {} \;

Now for the discussion. Your explanation make sense. Explicitly binding the last '-name' with the '-exec' sounds right, but that means the previous '-name' options are no-ops? Should that have caused an error message?

In the future I must remember to use parentheses.

Thanks for you input and time. I will makr this as solved.

rknichols · 11-02-2014, 05:59 PM

[QUOTE=MrUmunhum;5263517]

Quote:

Originally Posted by rknichols

but that means the previous '-name' options are no-ops? Should that have caused an error message?

All of those "options" are just elements in a boolean expression which can be quite complex. In cases like yours, it's easy to see that those terms could never cause evaluation of any action element, but in general that is not easy to determine. For the case where there is no action element at all, find does use a default action of "-print" if the overall expression evaluates to true, but if there is any action, find just evaluates the expression you supplied, and if that does not involve any action, so be it.

FWIW, the C compiler too does not require that a conditional expression result in any action that has side effects. The following is valid C and compiles without warnings, even with "-Wall" as long as variable x is defined and set. In fact, the pointless test gets optimized out entirely.

Code:

if(x == 5) { }

Quote:

In the future I must remember to use parentheses.

We've all made that same mistake. In fact, I made it myself about an hour after posting my reply.