Ambiguous Redirect error while accessing cmd line arg in a function

[ram]

I am writting a script to do below activities on a numFile having a set of numbers:
1. Addition
2. Average
3. Max/Min

With Addition code , below error message is coming.

code:
sum=0

sumNumber() ## to sum the numbers from file
{
while read n
do
(( sum+=n ))
done < $1
}
while getopts ":samn" optchar
do
case $optchar in
s) shift ## s - SUM of Number
sumNumber
echo "Sum = "$sum
;;
.
.

calling: $./getOpts -s numFile
error: ./getOpts1: line 14: $1: ambiguous redirect


let me know:
In function body can't we access the command line arguments $1,$2.. after we have used "shift" before calling the function

[Kaz Kylheku]

On 2012-10-10, ram <bhatnaga...@gmail.com> wrote:
> sumNumber() ## to sum the numbers from file
> {
> while read n
> do
> (( sum+=n ))
> done < $1
> }

$1 is the argument to the function sumNumber

> while getopts ":samn" optchar
> do
> case $optchar in
> s) shift ## s - SUM of Number
> sumNumber

You didn't pass an argument to sumNumber. So $1 expands to nothing.

Add "set -u" at the top of the script to catch references to unset parameters.

> In function body can't we access the command line arguments $1,$2.. after we

No. Functions have their own arguments, and since names are not used but
positional parameters, the ones in the function shadow the global ones.

[Chris F.A. Johnson]

You must explicitly pass arguments to the function:

sumNumber "$1"

--
Chris F.A. Johnson, author <http://shell.cfajohnson.com/>
===================================================================
Shell Scripting Recipes: A Problem-Solution Approach (2005, Apress)
Pro Bash Programming: Scripting the GNU/Linux Shell (2009, Apress)

[Ed Morton]

ram <bhatnaga...@gmail.com> wrote:

> I am writting a script to do below activities on a numFile having a set
of numbers:
> 1. Addition
> 2. Average
> 3. Max/Min
>
> With Addition code , below error message is coming.
>
> code:
> sum=0
>
> sumNumber() ## to sum the numbers from file
> {
> while read n
> do
> (( sum+=n ))
> done < $1
> }
> while getopts ":samn" optchar
> do
> case $optchar in
> s) shift ## s - SUM of Number
> sumNumber
> echo "Sum = "$sum
> ;;
> ..

> ..

>
> calling: $./getOpts -s numFile
> error: ./getOpts1: line 14: $1: ambiguous redirect
>
>
> let me know:
> In function body can't we access the command line arguments $1,$2..
after we have used "shift" before calling the function

a) see the other answers, but more importantly:
b) don't do that in shell, do it in awk or perl or similar.

In awk you can do all of the above calculations with just:

awk '
{
sum += $0
max = ($0 > max ? $0 : max)
min = ($0 < min ? $0 : min)
}
END {
print "sum =", sum
print "ave =", sum / NR
print "min =", min
print "max =", max
}
' file

Regards,

Ed.

Posted using www.webuse.net

[Hermann Peifer]

On 2012-10-10 15:36, Ed Morton wrote:
> In awk you can do all of the above calculations with just:
>
> awk '
> {
> sum += $0
> max = ($0 > max ? $0 : max)
> min = ($0 < min ? $0 : min)
> }
> END {
> print "sum =", sum
> print "ave =", sum / NR
> print "min =", min
> print "max =", max
> }
> ' file
>

As a small side-remark: in case all input values happen to be 0's, min
and max will not be set and the above will print:


sum = 0
ave = 0
min =
max =

Hermann

[Ed Morton]

Yeah, you're right and while we're addressing that we may as well fix the END
block to print numbers even if the file is empty:

END {
printf "sum = %d\n", sum
printf "ave = %d\n", (NR ? sum / NR : 0)
printf "min = %d\n", min
printf "max = %d\n", max
}

or if we want "NaN"s printed in that situation:

END {
print "sum =", (NR ? sum + 0 : "NaN")
print "ave =", (NR ? sum / NR : "NaN")
print "min =", (NR ? min + 0 : "NaN")
print "max =", (NR ? min + 0 : "NaN")
}

Note that to force printing a numeric value (0) from a variable that may not
have been populated, you can use either:

printf "%d\n", var

or

print var + 0

I showed both ways above, it's a style choice.

Regards,

Ed.