#!/bin/bash
read n
sd=0
rev=0
if[[ $n -lt 0 ]];
then
echo "Not a positive number"
else
while [[ $n -gt 0 ]]
do
sd=$(( $n % 10 ))
rev=`expr $rev \* 10 + $sd`
n=$(( $n /10 ))
done
echo $rev
./scriptprog4.sh: line 6: if[[ 123 -lt 0 ]]: command not found
./scriptprog4.sh: line 7: syntax error near unexpected token then'
./scriptprog4.sh: line 7:then'
There was a missing fi statement (highly recommended to indent the code). Here's a working script:
#!/bin/bash
read n
sd=0
rev=0
if [[ $n -lt 0 ]]
then
echo "Not a positive number"
else
while [[ $n -gt 0 ]]
do
sd=$(( $n % 10 ))
rev=`expr $rev \* 10 + $sd`
n=$(( $n /10 ))
done
fi
echo $rev
and an execution:
$ ./scriptprog4.sh
123
321
expr is not good practice. It's a holdout from the 1970s; any shell compatible with the 1992 POSIX sh specification supports rev=$(( rev * 10 + sd )), which is both guaranteed to be available on any standard-compliant shell (expr is not), and more efficient (being built into the shell itself, as opposed to an external process)../scriptprog4.sh: line 6: if[[ 123 -lt 0 ]]: command not found
is caused by a missing space between if and [[ both are reserved words in bash and must be separated by space
if [[ $n -lt 0 ]]; then
