Define function in unix/linux command line (e.g. BASH)

Question

Sometimes I have a one-liner that I am repeating many times for a particular task, but will likely never use again in the exact same form. It includes a file name that I am

Answer 1

Quoting my answer for a similar question on Ask Ubuntu:

Functions in bash are essentially named compound commands (or code blocks). From man bash:

Compound Commands
   A compound command is one of the following:
   ...
   { list; }
          list  is simply executed in the current shell environment.  list
          must be terminated with a newline or semicolon.  This  is  known
          as  a  group  command. 

...
Shell Function Definitions
   A shell function is an object that is called like a simple command  and
   executes  a  compound  command with a new set of positional parameters.
   ... [C]ommand is usually a list of commands between { and },  but
   may  be  any command listed under Compound Commands above.

There's no reason given, it's just the syntax.

Try with a semicolon after wc -l:

numresults(){ ls "$1"/RealignerTargetCreator | wc -l; }