Shell Programming and Scripting

I'm always concerned I might be abusing backticks within my scripts. A current script I'm writing has this for example:

stripscriptname=`echo $scriptname | sed 's/\(.*\)\..*/\1/'`
stripsearch=`echo $searchpattern | tr -d ' ,/'`

Both of these variables are set inside the script (in fact, $scriptname is set with "scriptname=`basename $0`") so it seems to me that I shouldn't need to use backticks but I don't know a better way to do this.

Am I abusing backticks? Is there a better way to accomplish what I did in the above examples?

MG

I might write:

Code:

stripscriptname=$(sed 's/\(.*\)\..*/\1/' <<< "$scriptname")
stripsearch=$(tr -d ' ,/' <<< "$searchpattern")

I think avoiding the echo cuts out one extra process, builtin or not.

Is the purpose of your sed search string to strip off any string beginning with dot from the end of the string? It might work faster(and more portably, since it needs no backreferences) to just match and delete the portion you don't want without matching the part you want to keep:

Code:

sed 's/\..*//'

Some shells, like bash 3 and newer, support built-in regular expressions without resort to sed.

Use parameter expansion; it's many times faster than calling an external command. For example, instead of

Code:

scriptname=`basename $0`

Use:

Code:

scriptname=${0##*/}

To remove an extension:

Code:

stripscriptname=${scriptname%.*}