Shell Programming and Scripting

I have a strange issue.

Code:

(awk '$3 == "nfs" { cnt++ }; END { print cnt }' /etc/fstab)

This is giving different count each time.


To test this, tried the one here

Code:

-bash-3.2$ awk '/nfs/{print $2}' /etc/fstab | wc -l
151
-bash-3.2$ awk '/nfs/{print $2}' /etc/fstab | wc -l
145
-bash-3.2$ awk '/nfs/{print $2}' /etc/fstab | wc -l
150

checking the output, it has all wired outputs each time, since command was searching for "nfs", it is giving all non matched strings. output were always different.

do
/boot
/tmp
/var
none
/dev/pts

The same script is working on all other 100+ machines, only one machine is showing the wired stuff.

its not an issue with file type, its happening with every file

Code:

552
-bash-3.2$ awk '/bash/{print $1}' /etc/passwd | wc -l
556
-bash-3.2$ awk '/bash/{print $1}' /etc/passwd | wc -l
552

-bash-3.2$ awk '/nfs/{print $1}' /proc/mounts | wc -l
147
-bash-3.2$ awk '/nfs/{print $1}' /proc/mounts | wc -l
145

any ideas/thoughts ?

Yes, that seems pretty strange. I assume when you use grep in a similar way to how you are using awk, to count the number of matching lines, there is no problem? In other words, does grep always give the same count of /etc/passwd lines with the word "bash"? And do you know for sure what the "right" answers are in each case? Does awk usually give the right answer, or wrong answer?

Have you tried "which awk" and investigating the file that it reports? Kind of a reality check.

grep is correct, thats my work around for the time being..

this issue looks really wierd, I even tried to reinstall the gawk pkg, still issue persists

/bin/awk which is linked from /bin/gawk


The thing is awk give right sometimes, sometimes the same command even displays non matched strings.

say here in the fstab, its giving


do
/boot
/tmp
/var
none
/dev/pts

which does not have an "nfs" keyword

Have you checked the md5sum on gawk executable, compared with that on other machines? Since you re-installed, I'm just clutching at straws.

IMO, you really need to figure out why this is happening. We all know from many years of experience that there is no "magic". There is always an explanation, and some funky behavior like this has to be diagnosed and fixed. There is something weird going on, awk printing lines without a match. Logically, either the input file is changing (but would not explain awk reporting non-matching lines), or awk is damaged (seems impossible since you re-installed), or a hardware problem (?), or something else (no guess). I hope that machine is not doing anything mission-critical. If you have 100+ machines, and awk continues to malfunction, maybe this machine should be sold off?

What happens if you copy /etc/fstab to your user directory, and run awk as the user instead of as root? Or vice versa? Again, just clutching at straws.

hanson44,

all giving wrong outputs, tried almost all things what you mentioned already.

but yea I will track this down, may need some more time

That is really strange. I have some other experts on the forum, probably smarter than me, have some ideas.

If it's only happening on one machine, I would suspect problems like disk or memory errors.