If condition fails for special charecter

Shell Programming and Scripting
1

I have a sample server name listed in variable as below:

var="server-13"

I need to check if the 7th character on $var is number 1

 
 whichenv=`echo "$var"| head -c 7 | tail -c 1`

if [[ $whichenv -eq "9" ]]; then
echo "9 found"
 else
echo "9 Not Found"
fi

Output:

This works fine but fails only if the seventh character is a hyphen "-".

Can you please suggest how can I overcome this issue ?

2 
[ "${var:7:1}" == 1 ]

must be enclosed in double quotes and compare strings.
Your code will work the same way.

3

-eq does not exist in a double bracket expression, hence the syntax error. Either use (pattern matching)

if [[ $whichenv == 9 ]]

or (arithmetic comparison expression)

if (( whichenv == 9 ))

Note that whichenv does not contain the right value (this is not delivered by the head and tail utilities )
Try for example

whichenv=${var#*-}

To get the number behind the dash

--

Note: the OP was using a double bracket expression, where these quotes are not necessary..
With single brackets the correct expression is either (string comparison):

[ "$var" = 1 ]

or (numerical comparison)

[ "$var" -eq 1 ]
3 Likes
4

Thank you this works !!