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redirection error

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# 1  
Old 04-28-2011
redirection error
Hi i am facing a very strange problem

suppose the parameters which i passed to the script is

Code:
-o 140

then my code is as follows
Code:
 echo $* | awk '{ for ( i=0;i<=NF;i++){if ($i= -o) { print ${i+1} } } ' | read abc
echo $abc

abc=`echo $* | awk '{ for ( i=0;i<=NF;i++){if ($i= -o) { print ${i+1} } } '`
echo $abc
140

why this is happening in case of read abc parameter
# 2  
Old 04-28-2011
Quote:
Originally Posted by aishsimplesweet
Hi i am facing a very strange problem

suppose the parameters which i passed to the script is

Code:
-o 140

then my code is as follows
Code:
 echo $* | awk '{ for ( i=0;i<=NF;i++){if ($i= -o) { print ${i+1} } } ' | read abc
echo $abc

abc=`echo $* | awk '{ for ( i=0;i<=NF;i++){if ($i= -o) { print ${i+1} } } '`
echo $abc
140

why this is happening in case of read abc parameter
I even doubt you can run this code, and the syntax your redirecting to read is wrong.
It should be:
Quote:
read abc <<< `awk '{print}' infile`
# 3  
Old 04-28-2011
As Kevin marked them red, these braces should be (), not {}; when correcting them, you are missing a closing }.
That read will fill your variable abc, but not the positional parameter $*. $* will be empty, since there aren't any parameters this way.

Try this:
Code:
$ read LINE; echo $LINE |awk '{for(i=1;i<=NF;i++){if($i=="-o"){print $(i+1)}}}'
hello -o printme -a lala -o printmetoo aaabbb ccc
printme
printmetoo

To check parameters you could also use case/esac or getopts for example.
# 4  
Old 04-29-2011
hi everyone

sry i have wrongly copied the code the actual part of code in my script is as follows

it is the actual code please please help me reagrding this

Code:
 
echo $*
-o 140
 
echo $* | awk '{    for ( i=1; i<=NF; i++ ) { if ($i=="-O" || $i=="-o") { print $(i+1) } } }' | read abc
echo $abc
 
abc=`echo $* | awk '{    for ( i=1; i<=NF; i++ ) { if ($i=="-O" || $i=="-o") { print $(i+1) } } }'`
echo $abc
140

# 5  
Old 04-29-2011
We already wrote something - maybe try the solutions and correct your code? Give feedback? Thank you.
# 6  
Old 04-29-2011
Most shells will run that read command in a subshell. abc will be set in the subshell. The subshell exits as soon as the read is completed. Since changes in a subshell's execution environment are not visible in parents or siblings, the variable abc is left unchanged in the original shell.

If your shell behaves in this way, the following are equivalent and both will print an empty line:
Code:
echo hello | read x
echo $x

echo hello | ( read x )
echo $x

But this will print "hello" since the $x is used within the subshell where it has the value that was read:
Code:
echo hello | ( read x; echo $x )

POSIX allows the shell to run any component of a pipeline in a subshell.

Regards,
Alister
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