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Input value changing into 0

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# 1  
Old 02-22-2013
Input value changing into 0
Hi,

I am getting a strange problem in my production environment.

Line in input file:
Code:
[ASD_HAGDF_CSAS_CMPPRD.s_PRDPR_STNNSTN_CSAS_SRCTPP_COMMHIST006_INC_dat_LD]

Code:
Code:
while read myline
do
echo $myline >> /home/aauytrf/PARM_FILE_NM.bak
fi
done < /home/aauytrf/PARM_FILE_NM.prm

Output:
Code:
0

Here the input line is becoming 0. This is not happening to all lines in the input file, only to some lines alone.

Strangest thing is I am unable to re-craete this issue in my test environment.

Can some one shed some light into what is going wrong here.

Regards
niba
Last edited by Scrutinizer; 02-22-2013 at 06:24 PM.. Reason: code tags
# 2  
Old 02-22-2013
Quote:
Originally Posted by niba
while read myline
do
echo $myline >> /home/aauytrf/PARM_FILE_NM.bak
fi
done < /home/aauytrf/PARM_FILE_NM.prm
Why there is a fi statement in your while loop?

Also always wrap string variables in double quotes:
Code:
while read myline
do
    echo "$myline" >> /home/aauytrf/PARM_FILE_NM.bak
done < /home/aauytrf/PARM_FILE_NM.prm

# 3  
Old 02-22-2013
Thats a type there is no if statement. Code is

Code:
 while read myline
do
echo $myline >> /home/aauytrf/PARM_FILE_NM.bak
done < /home/aauytrf/PARM_FILE_NM.prm

One more point the script does not contain #! as the first line, so I am not sure whihc interpreter is used to execute. My script is called from another script which has #!/usr/bin/ksh, so I think it is korn shell.
# 4  
Old 02-23-2013
Not sure I understand. What output is "0"? Do you have a line
Code:
0

in your .bak file? Pls post more meaningful input and output samples, and maybe an execution log of your script. From what I see in your post, there's no indication of sth. going wild.
# 5  
Old 02-23-2013
OK I think I know what's up...
From the READ manual...

Code:
If count is zero, read() returns zero and has  no  other  results.   If
       count is greater than SSIZE_MAX, the result is unspecified

Also I did a little test...

Code:
cat test.txt

[ASD_HAGDF_CSAS_CMPPRD.s_PRDPR_STNNSTN_CSAS_SRCTPP_COMMHIST006_INC_dat_LD]
[bla.bla]
 [bla.bla] [bla.bla]
\[bla.bla\]
No.Brackets.Bla.Bla
[NO_PERIODS]
[NO.UNDERSCORE]

my results using bash with the debug option....
Code:
#!/bin/bash
while read myline
do
echo $myline 
done < test.txt
+ read myline
+ echo a
a
+ read myline
+ echo a b
a b
+ read myline
+ echo a b a b
a b a b
+ read myline
+ echo a b
a b
+ read myline
+ echo No.Brackets.Bla.Bla
No.Brackets.Bla.Bla
+ read myline
+ echo '[NO_PERIODS]'
[NO_PERIODS]
+ read myline
+ echo '[NO.UNDERSCORE]'
[NO.UNDERSCORE]
+ read myline
+ echo

+ read myline

So I think what happens is that the ^[ or [bl la] is being interpreted as a type of non ASCII character. When I tranpose the brackets on either side of your original string...it shows up...

Code:
#!/bin/bash
while read myline
do
echo $myline 
done < test.txt
+ read myline
+ echo a
a
+ read myline
+ echo a b
a b
+ read myline
+ echo a b a b
a b a b
+ read myline
+ echo a b
a b
+ read myline
+ echo No.Brackets.Bla.Bla
No.Brackets.Bla.Bla
+ read myline
+ echo '[NO_PERIODS]'
[NO_PERIODS]
+ read myline
+ echo '[NO.UNDERSCORE]'
[NO.UNDERSCORE]
+ read myline
+ echo ']ASD_HAGDF_CSAS_CMPPRD.s_PRDPR_STNNSTN_CSAS_SRCTPP_COMMHIST006_INC_dat_LD['
]ASD_HAGDF_CSAS_CMPPRD.s_PRDPR_STNNSTN_CSAS_SRCTPP_COMMHIST006_INC_dat_LD[
+ read myline

I would use a different manner of backing up...
# 6  
Old 02-24-2013
That quote is referring to the read C library function, not the shell's read command. Two different things.
I cannot reproduce your test. When running that code snippet on your test.txt file, lines are output as is except for some whitespace removal.
# 7  
Old 02-24-2013
What does
Code:
while read myline
do
  printf "%s\n" "$myline"
done < /home/aauytrf/PARM_FILE_NM.prm >> /home/aauytrf/PARM_FILE_NM.bak

produce?

For a literal copy use:
Code:
while IFS= read -r myline
do
  printf "%s\n" "$myline"
done < /home/aauytrf/PARM_FILE_NM.prm >> /home/aauytrf/PARM_FILE_NM.bak

But why isn't cat being used instead?
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