I can't understand return value of gawk.

jpmon · 03-10-2010, 04:43 AM

I write a little script by bash.
-------------------------------------------------------------------------
#!/bin/bash
a=`gawk '/Iterations /{print $0}' hoge.log | gawk 'BEGIN{FS=" "}{print ($4)}'`
a=`expr 3 '*' $a`
-------------------------------------------------------------------------
hoge.log is below text.
-- Iterations = 50000

Above srcipt can run in cygwin, Display "150000"
but can't run in Linux, Display "expr: non-numeric argument"
What is different for Linux and cygwin?
I would like tell me how is wrong.

catkin · 03-10-2010, 04:53 AM

It works as you expect for me on Linux (Slackware 13.0).

What is $a after a=`<gawk pipe>` and before a=`expr command>`?

jpmon · 03-10-2010, 08:04 PM

I would like to read a lot of log files like "hoge*.log",
and extract data to calc for one purpose.

I can't use bc in my system.
Would you tell me alternative way?

catkin · 03-10-2010, 08:38 PM

Quote:

Originally Posted by jpmon

I would like to read a lot of log files like "hoge*.log",
and extract data to calc for one purpose.

I can't use bc in my system.
Would you tell me alternative way?

An alternative to bc is expr. If you answered my question it might help us find out why expr is not working for you -- and then we might be able to make it work.

What is the output if you modify the script to

Code:

#!/bin/bash
a=`gawk '/Iterations /{print $0}' hoge.log | gawk 'BEGIN{FS=" "}{print ($4)}'`
echo "a is '$a'"
a=`expr 3 '*' $a`

sundialsvcs · 03-10-2010, 10:28 PM

And this is hardly a "linux kernel" question . . .

jpmon · 03-11-2010, 12:30 AM

I ran above code.
One log write by vi and Other dump by other executable program.

write by vi
Display "a is '50000'".

dump by other executable program
Display "' is '50000".
I think last character "'" comes around at head of the line.
Dump use only redirect.
What is different?

catkin · 03-11-2010, 12:52 AM

Quote:

Originally Posted by jpmon

I ran above code.
One log write by vi and Other dump by other executable program.

write by vi
Display "a is '50000'".

dump by other executable program
Display "' is '50000".
I think last character "'" comes around at head of the line.
Dump use only redirect.
What is different?

What does "dump by other executable program" mean? Did you copy-and-paste the output from running the script?

jpmon · 03-11-2010, 01:56 AM

Other executable program is benchmark program.
I making this script for assembling result data from benchmark program's dump.

catkin · 03-11-2010, 03:15 AM

Quote:

Originally Posted by jpmon

Other executable program is benchmark program.
I making this script for assembling result data from benchmark program's dump.

Can we keep it simple to start with and just run the script from the command line and copy-and-paste the output to ensure it is exactly what the script wrote? Once that's known to be working OK we can move onto running it in other ways.

pixellany · 03-11-2010, 08:24 AM

moved to Programming

colucix · 03-11-2010, 09:05 AM

Quote:

Originally Posted by jpmon

Above srcipt can run in cygwin, Display "150000"
but can't run in Linux, Display "expr: non-numeric argument"
What is different for Linux and cygwin?

Most likely you're trying to read in Linux a log file created in Windows. Different line terminators between the two systems cause troubles to the shell. To avoid the problem, in Linux you can try

Code:

dos2unix hoge.log

before running the script.

A little hint: you can summarize your statements with a single awk line, e.g. with something like:

Code:

a=`gawk '/Iterations /{print $4*3}' hoge.log`

ghostdog74 · 03-11-2010, 07:47 PM

Quote:

Originally Posted by jpmon

I write a little script by bash.
-------------------------------------------------------------------------
#!/bin/bash
a=`gawk '/Iterations /{print $0}' hoge.log | gawk 'BEGIN{FS=" "}{print ($4)}'`
a=`expr 3 '*' $a`
-------------------------------------------------------------------------
hoge.log is below text.
-- Iterations = 50000

Above srcipt can run in cygwin, Display "150000"
but can't run in Linux, Display "expr: non-numeric argument"
What is different for Linux and cygwin?
I would like tell me how is wrong.

why are you doing an extra pipe to gawk? you can do it with just one gawk statement

Code:

gawk '/Iterations/{  print $4 * 3}' hoge.log

to put the result to shell variable

Code:

a=$(gawk '/Iterations/{  print $4 * 3}' hoge.log)

ghostdog74 · 03-11-2010, 07:48 PM

Quote:

Originally Posted by catkin

An alternative to bc is expr. If you answered my question it might help us find out why expr is not working for you -- and then we might be able to make it work.

What is the output if you modify the script to

Code:

#!/bin/bash
a=`gawk '/Iterations /{print $0}' hoge.log | gawk 'BEGIN{FS=" "}{print ($4)}'`
echo "a is '$a'"
a=`expr 3 '*' $a`

expr cannot do floats.

jpmon · 03-11-2010, 11:27 PM

Thank you for the help.
I closure of problem.

The new-line character in my log file is CF+RF.
Inserting "dos2unix hoge.log" in my script, it run well!!!