Bad substitution error in shell script

Shell Programming and Scripting
1

I have script data.sh which has following error.

Script Name : data.sh

#!/bin/sh
infile=$1

len=${#infile} 
echo $len

texfile=${infile:0:$len-4}
echo $texfile

run command

./data.sh acb.xml

I get following error message:

./data.sh: 7: Bad substitution

May i know where i am wrong? How to fix this pblm?

2

As a guess: the shebang is calling a POSIX shell that does not support the syntax.

Change the first line of the script to:

#!/bin/bash

So we do not guess, please let us know what UNIX you are using and your shell.

3

Even with a #! change, I think something like this is needed:

 ${infile:0:$((len-4))}

as long as bin/sh is a bash or kshell.

4

Works with bash:-

# cat substr.sh
#!/bin/bash
infile=$1

len=${#infile}
echo $len

texfile=${infile:0:$len-4}
echo $texfile

# ./substr.sh bipinajith
10
bipina
5

@agama, don' think ksh supports the substring expansion and certainly bash will evaluate the length field so ${infile:0:len-4} is acceptable.

1 Like
6

I tried in Kshell -- it needed $(( ... )) and assumed that bash required the same. My bad for not testing with bash.

Thanks.