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 pasting in from a directory listing. Somewhere in between and creating a bash script I thought maybe I could just create a one-liner function at the command line like:
numresults(){ ls "$1"/RealignerTargetCreator | wc -l }
I've tried a few things like using eval, using numresults=function..., but haven't stumbled on the right syntax, and haven't found anything on the web so far. (Everything coming up is just tutorials on bash functions).
Quoting my answer for a similar question on Ask Ubuntu:
Functions in
bashare essentially named compound commands (or code blocks). Fromman 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; }
Don't use ls | wc -l as it may give you wrong results if file names have newlines in it. You can use this function instead:
numresults() { find "$1" -mindepth 1 -printf '.' | wc -c; }
You can also count files without find. Using arrays,
numresults () { local files=( "$1"/* ); echo "${#files[@]}"; }
or using positional parameters
numresults () { set -- "$1"/*; echo "$#"; }
To match hidden files as well,
numresults () { local files=( "$1"/* "$1"/.* ); echo $(("${#files[@]}" - 2)); }
numresults () { set -- "$1"/* "$1"/.*; echo $(("$#" - 2)); }
(Subtracting 2 from the result compensates for . and ...)