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# 1  
Old 12-14-2008
need help with awk
Hello,
when i try to combine find and awk.
In the directory /opt there are 2 files:
test1_data.txt
test2_error.txt

Code:
find /opt/test* | awk '{FS="_"} {print $1}'

and i get:
Code:
test1_data.txt
test2

why does the awk only work correct for the second file?
what am i doing wrong?

thank you for helping me
# 2  
Old 12-14-2008
Hi,

i don't know about the oddities of awk, but this works:

Code:
find test* | sed 's/_.*$//'

or this:

Code:
sed 's/_.*$//' < <(find test*)

HTH Chris
# 3  
Old 12-14-2008
Hey,
the problem is that i want to use awk, because i need to compare numbers of file names:

test1_150.txt
test2_120.txt
test3_180.txt

Code:
find /opt/test* | awk '{FS="_"} $2>130 {print $1}'

i should get
Code:
/opt/test1
/opt/test3

but the outcome is
Code:
/opt/test3

the code works for all found files except the first file.
awk stores the whole filename in $1 even if I set the FS to "_".
# 4  
Old 12-14-2008
The field separator is must be set before awk reads the first record.

Code:
awk -F_  '{print $1}'

or:

Code:
awk 'BEGIN{FS="_"}{print $1}'

Regards
# 5  
Old 12-14-2008
hey franklin
that works fine, thank you very much for your help
# 6  
Old 12-14-2008
perhaps these words listed below are useful for you
Quote:
According to the POSIX standard, awk is supposed to behave as if each record is split into fields at the time it is read. In particular, this means that if you change the value of FS after a record is read, the value of the fields (i.e., how they were split) should reflect the old value of FS, not the new one.

However, many implementations of awk do not work this way. Instead, they defer splitting the fields until a field is actually referenced. The fields are split using the current value of FS! (d.c.) This behavior can be difficult to diagnose. The following example illustrates the difference between the two methods. (The sed18 command prints just the first line of /etc/passwd.)

sed 1q /etc/passwd | awk '{ FS = ":" ; print $1 }'

which usually prints:

root

on an incorrect implementation of awk, while gawk prints something like:

root:nSijPlPhZZwgE:0:0:Root:/:
# 7  
Old 12-14-2008
@ivhb: That's exactly the problem I've experienced.

According to franklin52, it's the best way to fill the FS value first with the -F_ appendix:
Code:
awk -F_ '[...]'

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