Basic shell scripting expr command not working

Question

I'm trying a very simple example of expr command to add a number to a variable. However, everytime I print it this is what I get :

Code :

MY=1

MY= expr $MY+1

// for some reason when i'm putting both the back ticks here, they disappear.

echo $MY

Output:

1+1

Why doesn't the output come as 2 in this case ? I've made sure those are back ticks and the spacing is right.

Also, when I use print instead of echo, it shows print doesn't exist.

Xuan Nguyen Mai · Accepted Answer · 2013-12-04 03:22:54Z

1

You should add space to around +. Like this:

MY=`expr $MY + 1`

Because if you missed the space $MY+1, the shell will consider it as a string "1+1"

answered Dec 4, 2013 at 3:22

Xuan Nguyen Mai

1345 bronze badges

Sign up to request clarification or add additional context in comments.

2 Comments

rbk Over a year ago

Thanks, that worked ! Also, I just realized if I don't put #!/bin/bash at the start for it to realize it is a script, it still works. Any idea why that happens ?

Xuan Nguyen Mai Over a year ago

It always works. If you don't put "#!/bin/bash" at the start, the program will use the 'default' shell in your machine. Maybe the default shell is "/bin/sh". Putting "#!/bin/bash" will the your shell use correct bash instead of the default

Collectives™ on Stack Overflow

Basic shell scripting expr command not working

1 Answer 1

2 Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

2 Comments

Your Answer

Sign up or log in

Post as a guest

Related