How do I decide whether to make a command a shell script or an alias? [closed]

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http://unix.stackexchange.com – Possible Duplicate: In Bash, when to alias, when to script, and when to write a function? If I want to make a command like gsb that will expand to something like git show-branch -a | more or something even longer, what are the pros and cons of using a bash shell alias vs making a bash script and putting it on your PATH? Are there any performance considerations? For instance, does creating a lot of aliases create more overhead than adding a lot of commands to a directory on your PATH? (HowTos)