Very Computer

by **Perry Whela** » Sat, 17 Jul 2004 02:45:46

How can I resolve this error:
./cpu_percentage: line 16: ((: ROW_0 = : syntax error: operand expected
(error token is " ")
./cpu_percentage: line 16: ((: ROW_0 = : syntax error: operand expected
(error token is " ")
./cpu_percentage: line 16: ((: ROW_0 = : syntax error: operand expected
(error token is " ")
./cpu_percentage: line 16: ((: ROW_0 = : syntax error: operand expected
(error token is " ")
./cpu_percentage: line 16: ((: ROW_0 = : syntax error: operand expected
(error token is " ")
./cpu_percentage: line 16: ((: ROW_0 = : syntax error: operand expected
(error token is " ")
./cpu_percentage: line 16: ((: ROW_0 = : syntax error: operand expected
(error token is " ")
./cpu_percentage: line 16: ((: ROW_0 = : syntax error: operand expected
(error token is " ")
./cpu_percentage: line 16: ((: ROW_0 = : syntax error: operand expected
(error token is " ")
10176147

(notice it does infact have the desired value too)
...from this code:

#!/bin/bash
COMMANDS="awk"
for i in $COMMANDS
do
X=`echo $i|tr [a-z] [A-Z]`
export $X=`which $i`
done
FILE="/proc/stat"
while read ARRAY_0
do
ROW_0=`echo "$ARRAY_0" | $AWK '/cpu0 / {print $2}'`
(( ROW_0 = $ROW_0 ))
done < $FILE
echo ${ROW_0}
exit 0

by **j..** » Sat, 17 Jul 2004 03:54:09

> How can I resolve this error:
> ./cpu_percentage: line 16: ((: ROW_0 = : syntax error: operand expected
> (error token is " ")
> ./cpu_percentage: line 16: ((: ROW_0 = : syntax error: operand expected
> (error token is " ")
> ./cpu_percentage: line 16: ((: ROW_0 = : syntax error: operand expected
> (error token is " ")
> ./cpu_percentage: line 16: ((: ROW_0 = : syntax error: operand expected
> (error token is " ")
> ./cpu_percentage: line 16: ((: ROW_0 = : syntax error: operand expected
> (error token is " ")
> ./cpu_percentage: line 16: ((: ROW_0 = : syntax error: operand expected
> (error token is " ")
> ./cpu_percentage: line 16: ((: ROW_0 = : syntax error: operand expected
> (error token is " ")
> ./cpu_percentage: line 16: ((: ROW_0 = : syntax error: operand expected
> (error token is " ")
> ./cpu_percentage: line 16: ((: ROW_0 = : syntax error: operand expected
> (error token is " ")
> 10176147

> (notice it does infact have the desired value too)
> ...from this code:

> #!/bin/bash
> COMMANDS="awk"
> for i in $COMMANDS
> do
> X=`echo $i|tr [a-z] [A-Z]`

This should be

X=`echo $i|tr '[a-z]' '[A-Z]'`

Quote:> export $X=`which $i`

This should be

export X=`which $i`

But I'm not sure why you're doing it.

1. Why are you uppercasing the name of awk? You don't use it anywhere,
and you reassign X in the next line anyway.

2. You pass which the name as it's set in i, not the uppercased name.

Quote:> done
> FILE="/proc/stat"
> while read ARRAY_0
> do
> ROW_0=`echo "$ARRAY_0" | $AWK '/cpu0 / {print $2}'`
> (( ROW_0 = $ROW_0 ))

What's this line intended to do? Why set a variable to the value it
currently has?

This is the reason for the error messages. If you really are trying to
do that, the syntax should be

ROW_0=$ROW_0

But there's no reason to do that I can see.

Quote:> done < $FILE
> echo ${ROW_0}
> exit 0

No output will be produced unless "cpu0 " is in the last line of the
file.

If what you're trying to do is get the second field from the cpu0 line
of /proc/stat, try this

#!/bin/bash
FILE="/proc/stat"
ROW_0=`awk '
/cpu0 / {print $2}
' $FILE`
echo ${ROW_0}

Joe
--
We can't all be heroes because someone has to sit on the curb and
clap as they go by.
- Will Rogers

by **Perry Whela** » Sat, 17 Jul 2004 05:01:23

> > How can I resolve this error:
> > ./cpu_percentage: line 16: ((: ROW_0 = : syntax error: operand expected
> > (error token is " ")
> > ./cpu_percentage: line 16: ((: ROW_0 = : syntax error: operand expected
> > (error token is " ")
> > ./cpu_percentage: line 16: ((: ROW_0 = : syntax error: operand expected
> > (error token is " ")
> > ./cpu_percentage: line 16: ((: ROW_0 = : syntax error: operand expected
> > (error token is " ")
> > ./cpu_percentage: line 16: ((: ROW_0 = : syntax error: operand expected
> > (error token is " ")
> > ./cpu_percentage: line 16: ((: ROW_0 = : syntax error: operand expected
> > (error token is " ")
> > ./cpu_percentage: line 16: ((: ROW_0 = : syntax error: operand expected
> > (error token is " ")
> > ./cpu_percentage: line 16: ((: ROW_0 = : syntax error: operand expected
> > (error token is " ")
> > ./cpu_percentage: line 16: ((: ROW_0 = : syntax error: operand expected
> > (error token is " ")
> > 10176147

> > (notice it does infact have the desired value too)
> > ...from this code:

> > #!/bin/bash
> > COMMANDS="awk"
> > for i in $COMMANDS
> > do
> > X=`echo $i|tr [a-z] [A-Z]`

> This should be

> X=`echo $i|tr '[a-z]' '[A-Z]'`

> > export $X=`which $i`

> This should be

> export X=`which $i`

> But I'm not sure why you're doing it.

> 1. Why are you uppercasing the name of awk? You don't use it anywhere,
> and you reassign X in the next line anyway.

> 2. You pass which the name as it's set in i, not the uppercased name.

> > done
> > FILE="/proc/stat"
> > while read ARRAY_0
> > do
> > ROW_0=`echo "$ARRAY_0" | $AWK '/cpu0 / {print $2}'`
> > (( ROW_0 = $ROW_0 ))

> What's this line intended to do? Why set a variable to the value it
> currently has?

> This is the reason for the error messages. If you really are trying to
> do that, the syntax should be

> ROW_0=$ROW_0

> But there's no reason to do that I can see.

> > done < $FILE
> > echo ${ROW_0}
> > exit 0

> No output will be produced unless "cpu0 " is in the last line of the
> file.

> If what you're trying to do is get the second field from the cpu0 line
> of /proc/stat, try this

> #!/bin/bash
> FILE="/proc/stat"
> ROW_0=`awk '
> /cpu0 / {print $2}
> ' $FILE`
> echo ${ROW_0}

> Joe
> --
> We can't all be heroes because someone has to sit on the curb and
> clap as they go by.
> - Will Rogers

Thanks Joe, but the reason for the while read i do is to take an accurate
snapshot of the /proc/stat file, rather than reading each time I get a
value.

I got it figured out, and now also realize (after rereading my bash book,
again) that my logic was borken before...

Here's what I did:
while read ARRAY_0
do
ROWS_0[$[++N]]=$ARRAY_0
done < $FILE

N=0
while [ $[++N] -le ${#ROWS_0[*]} ]
do
ALL_USER0=`echo "${ROWS_0[1]}" | $AWK '{print $2}'`
done

echo $ALL_USER0 ;#now works perfectly...

Very Computer

syntax error: operand expected (error token is " ")

syntax error: operand expected (error token is " ")

syntax error: operand expected (error token is " ")

syntax error: operand expected (error token is " ")