bash and arithmetic comparison: double quotes or not?

Posted by Martin on Super User See other posts from Super User or by Martin
Published on 2012-11-29T10:28:40Z Indexed on 2012/11/29 11:09 UTC
Read the original article Hit count: 381

Filed under:

bash

|

comparison

when comparing two integers in bash, do we have to put double quotes ? In the official document http://tldp.org/LDP/abs/html/comparison-ops.html I can read that double quotes should appear every time... But what is the differences in the following examples:

[ "$VAR" -eq "1" ]
[ $VAR -eq "1" ]
[ "$VAR" -eq 1 ]
[ $VAR -eq 1 ]

As I am curious, a took a look at Ubuntu init scripts in /etc/init.d and there are many usage of arithmetic comparison in it, at least [ "$VAR" -eq "1" ] and [ $VAR -eq 1 ] are used... but it seems no one really "knows" what is the official way to do it.

Thanks !

© Super User or respective owner

Related posts about bash

launching a program from bash causes bash to go to new prompt

as seen on Ask Ubuntu - Search for 'Ask Ubuntu'
When I run a program from the console, e.g. me@box:~$ firefox I expect the console to log error messages (I think this is std out or std err?) and other items from the program, firefox in this case. But today I notice that bash just opens the program and goes to a new prompt, e.g. me@box:~$… >>> More
How to debug a .bash_profile

as seen on Ask Ubuntu - Search for 'Ask Ubuntu'
I was updating my .bash_profile, and unfortunetly I made a few updates and now I am getting: env: bash: No such file or directory env: bash: No such file or directory env: bash: No such file or directory env: bash: No such file or directory env: bash: No such file or directory -bash: tar: command… >>> More
Every command fails with "command not found" after changing .bash_profile?

as seen on Ask Ubuntu - Search for 'Ask Ubuntu'
I was updating my .bash_profile, and unfortunetly I made a few updates and now I am getting: env: bash: No such file or directory env: bash: No such file or directory env: bash: No such file or directory env: bash: No such file or directory env: bash: No such file or directory -bash: tar: command… >>> More
Is there any fundamental difference between piping in mac and linux?

as seen on Super User - Search for 'Super User'
ps -e | grep bash sample output from a linux machine: 1128 pts/14 00:00:00 bash 7491 pts/7 00:00:00 bash 12651 pts/14 00:00:00 bash 16145 pts/2 00:00:00 bash sample output from a mac machine: 58352 ttys000 0:00.09 login -pfl username /bin/bash -c exec -la bash /bin/bash 58353 ttys000… >>> More
why is $0 set to -bash?

as seen on Ask Ubuntu - Search for 'Ask Ubuntu'
First login process name seems to be set to "-bash", but if I subshell then it becomes "bash". for example: root@nowere:~# echo $0 -bash root@nowere:~# bash root@nowere:~# echo $0 bash -bash is causing some scripts to fail, such as . /usr/share/debconf/confmodule exec /usr/share/debconf/frontend… >>> More

Related posts about comparison

Store comparison in variable (or execute comparison when it's given as an string)

as seen on Stack Overflow - Search for 'Stack Overflow'
Hello everyone. I'd like to know if the super-powerful python allows to store a comparison in a variable or, if not, if it's possible calling/executing a comparison when given as an string ("==" or "!=") I want to allow the users of my program the chance of giving a comparison in an string. For… >>> More
On StringComparison Values

as seen on Geeks with Blogs - Search for 'Geeks with Blogs'
When you use the .NET Framework’s String.Equals and String.Compare methods do you use an overloStringComparison enumeration value? If not, you should be because the value provided for that StringComparison argument can have a big impact on the results of your string comparison. The StringComparison… >>> More
Use Comparison Operators in SQL to Remove/Return Columns with Null Values

as seen on Internet.com - Search for 'Internet.com'
When you use the comparison operators in SQL with the Where clause, you can remove the columns with null values. >>> More
Use Comparison Operators in SQL to Remove/Return Columns with Null Values

as seen on Internet.com - Search for 'Internet.com'
When you use the comparison operators in SQL with the Where clause, you can remove the columns with null values. >>> More
Building a Web Form in ASP.NET and PHP: a Comparison

as seen on ASP Free - Search for 'ASP Free'
While there are important differences between PHP and ASP.NET both are used to build websites. Because of this both need to enable developers to build web forms among other tasks. This article compares building a web form in PHP with building the same form in ASP.NET to help those familiar with… >>> More