Unable to set a variable for loop

pedropt · 07-24-2017, 11:12 AM

Hi , i am trying to set a veriable for a loop depending on user choice , but somehow i am unable to figure out why i get :

Quote:

./test: line 8: 1t=1: command not found
./test: line 9: 2t=1 2: command not found
./test: line 10: 3t=1..3: command not found
./test: line 11: 4t=1..4: command not found
./test: line 12: 5t=1..5: command not found
./test: line 13: 6t=1..6: command not found
./test: line 14: 7t=1..7: command not found
./test: line 15: 8t=1..8: command not found
./test: line 16: 9t=1..9: command not found
./test: line 17: 10t=1..10: command not found

on this script .

Quote:

#!/bin/bash
lp(){
for i in "$var"
do
echo $i
done
}
1t="1"
2t="1 2"
3t="1..3"
4t="1..4"
5t="1..5"
6t="1..6"
7t="1..7"
8t="1..8"
9t="1..9"
10t="1..10"

echo -n "select 1 to 10 ."
read -r sel
case $sel in
1)
var="$1t"
lp
;;
2)
var="$2t"
lp
;;
3)
var="$3t"
lp
;;
4)
var="$4t"
lp
;;
5)
var="$5t"
lp
;;
6)
var="$6t"
lp
;;
7)
var="$7t"
lp
;;
8)
var="$8t"
lp
;;
9)
var="$9t"
lp
;;
10)
var="$10t"
lp
;;
*)
echo "Only a number between 1 and 10 is available"
exit 1
;;
esac

hydrurga · 07-24-2017, 11:16 AM

As far as I aware, Bash shell variable names must start with a letter or an underscore, and thus not a digit.

pedropt · 07-24-2017, 11:32 AM

Yup you are right .
However it is interesting that when i set a $var for the number of times i want to loop , the
function :

Quote:

for i in $var
do
echo $i
done

does not accept the current variable !!
anyone have a idea why ?

here it is the code :

Quote:

#!/bin/bash
lp(){
for i in $var
do
echo $i
done
}
t1="1"
t2="{1 2}"
t3="{1..3}"
t4="{1..4}"
t5="{1..5}"
t6="{1..6}"
t7="{1..7}"
t8="{1..8}"
t9="{1..9}"
t10="{1..10}"

echo -n "select 1 to 10 ."
read -r sel
case $sel in
1)
var="$t1"
lp
;;
2)
var="$t2"
lp
;;
3)
var="$t3"
lp
;;
4)
var="$t4"
lp
;;
5)
var="$t5"
lp
;;
6)
var="$t6"
lp
;;
7)
var="$t7"
lp
;;
8)
var="$t8"
lp
;;
9)
var="$t9"
lp
;;
10)
var="$t10"
lp
;;
*)
echo "Only a number between 1 and 10 is available"
exit 1
;;
esac

pedropt · 07-24-2017, 12:07 PM

Well , i did a quick search on the web for this issue and i found a solution to get around it .

Code:

#!/bin/bash
lp(){
for i in $(seq "$var")
do
echo $i
done
}
t1="1"
t2="2"
t3="3"
t4="4"
t5="5"
t6="6"
t7="7"
t8="8"
t9="9"
t10="10"

echo -n "select 1 to 10 ."
read -r sel
case $sel in
1)
var="$t1"
lp
;;
2)
var="$t2"
lp
;;
3)
var=$(t3)
lp
;;
4)
var="$t4"
lp
;;
5)
var="$t5"
lp
;;
6)
var="$t6"
lp
;;
7)
var="$t7"
lp
;;
8)
var="$t8"
lp
;;
9)
var="$t9"
lp
;;
10)
var="$t10"
lp
;;
*)
echo "Only a number between 1 and 10 is available"
exit 1
;;
esac

NevemTeve · 07-24-2017, 12:56 PM

Kindly use [code] instead of [quote]:

Code:

The rigth way

Quote:

Not this

astrogeek · 07-24-2017, 02:15 PM

As noted by others, please place your code snippets inside [CODE]...[/CODE] tags (not QUOTE tags), for better readability. You may type those yourself or click the "#" button in the edit controls.

In your for loop, $var is expanded as a string, not evaluated as a range specification. Similarly, your assignments, t1-10 are just strings and do not generate the ranges.

You need to rethink completely how that works.

As your loop always begins at 1, maybe you should pass it a limit value instead and perhaps use a while loop which breaks when the limit s reached.

Either way, I would refer you to man bash Compound commands for a better understanding of how those loop constructs actually work.

suicidaleggroll · 07-24-2017, 03:43 PM

Quote:

Originally Posted by pedropt

Well , i did a quick search on the web for this issue and i found a solution to get around it .

Code:

#!/bin/bash
lp(){
for i in $(seq "$var")
do
echo $i
done
}
t1="1"
t2="2"
t3="3"
t4="4"
t5="5"
t6="6"
t7="7"
t8="8"
t9="9"
t10="10"

echo -n "select 1 to 10 ."
read -r sel
case $sel in
1)
var="$t1"
lp
;;
2)
var="$t2"
lp
;;
3)
var=$(t3)
lp
;;
4)
var="$t4"
lp
;;
5)
var="$t5"
lp
;;
6)
var="$t6"
lp
;;
7)
var="$t7"
lp
;;
8)
var="$t8"
lp
;;
9)
var="$t9"
lp
;;
10)
var="$t10"
lp
;;
*)
echo "Only a number between 1 and 10 is available"
exit 1
;;
esac

Isn't that just an incredibly long and convoluted way of doing this:

Code:

if [[ ($# == 1) && ($1 =~ [0-9]?[0-9]) && ($1 -le 10) ]]; then
   seq $1
else
   echo "Only a number between 1 and 10 is available"
fi