Integer comparison in bash

Question

I need to implement something like:

if [ $i -ne $hosts_count - 1] ; then cmd="$cmd;" fi 

But I get

./installer.sh: line 124: [: missing `] '

What am I doing wrong?

Answer 1

The command [ cannot process arithmetic inside its test. Change it to:

 if [ $i -ne $((hosts_count-1)) ]; then 

Edit: what @cebewee wrote is also true; you must put a space before closing ] . But only this will lead to another error: extra argument '-'

Answer 2

• ] must be a separate argument [ .

• You assume you can do the math in [ .

   if [ $i -ne $(($hosts_count - 1)) ] ; then 

Answer 3

In bash, you can avoid both [ ] and [[ ]] by using (( )) for purely arithmetic conditions:

 if (( i != hosts_count - 1 )); then cmd="$cmd" fi 

Answer 4

Closing ] must be preceded by a space, ie write

 if [ $i -ne $hosts_count - 1 ] ; then cmd="$cmd;" fi