On many systems, #!/usr/bin/env utility will work for many common cases.

On systems that support multiple programming environments (like Solaris systems that use $PATH to choose between SVID3, XGP3, XPG4, XPG5, XPG6, old BSD, etc. environments), something like #!/usr/bin/env cmd where cmd is sh, awk, grep, sed, or any other utility that has different versions depending on the environment chosen) might or might not give you what you want depending on how PATH is set by the user invoking your script.

Since I worked at Sun for more than twenty years, I almost never use #!/usr/bin/env. And, I would never use that in any script that I would expect to ever be run on a Solaris system to get access to any utility that uses internationalized regular expressions.

Note also that I frequently see people posting scripts that use:

Code:

#!/usr/bin/env utility arg1 arg2 ...

or:

Code:

#! /usr/bin/env utility arg1 arg2 ...

but on some systems (at least in the late 1980's and early 1990's when the first version of the POSIX utilities standard was being developed) everything following the #! is treated as the name of the interpreter to be invoked. On those systems (if any still exist):

Code:

#!/usr/bin/env bash

will fail unless there is a utility named env<space>bash in /usr/bin. And, I'm pretty sure that there are still systems that will accept an interpreter name and one argument to it (as in the above invocation of bash), but won't accept more than one argument, such as in:

Code:

#!/usr/bin/env bash -xv