In most shells, aliases are an easy way to shorten a long command line or do a short series of commands. Section 29.2 through Section 29.10 cover C shell aliases. Section 29.4 through Section 29.14 cover aliases in bash, pdksh, and zsh.
All except the oldest Bourne-type shells have shell functions (Section 29.11), which are explained in Section 29.11 through Section 29.13. These are a cross between aliases and shell scripts. They’re good both for shortening command lines and for running a short or long series of commands.
—JP and SJC
All shells except the original Bourne shell have an “alias” facility that lets you define abbreviations for commands.
The simplest C shell aliases, which are similar to the alias facility in newer Bourne-type shells, are simply a short name for a command and, often, command options or arguments too. The C shell’s aliases can get very complicated. Section 29.3 describes how a C shell alias can use arguments from its command line as it’s invoked.
As we’ve said, aliases in Bourne-type shells (bash , zsh, and ksh) are simpler. Section 29.4 covers some of the differences between those shells and the C shells. Still, the ideas for custom C shell commands are useful in any kind of shell, and if you can’t write something in a simple Bourne-type alias, you almost certainly can do it in a shell function ( Section 29.11).
You can define aliases from the command line, for use in just ...