Avoiding Aliases, Functions
Problem
You’ve written an alias or function to override a real command, and now you want to execute the real command.
Solution
Use the bash shell’s builtin command to ignore shell functions and aliases to run the actual built-in command.
Use the command command to ignore shell functions and aliases to run the actual external command.
If you only want to avoid alias expansion, but still allow function definitions to be considered, then prefix the command with \ to just prevent alias expansion.
Use the type command (also with -a) to figure out what you’ve got.
Here are some examples:
$ alias echo='echo ~~~' $ echo test ~~~ test $ \echo test test $ builtin echo test test $ type echo echo is aliased to `echo ~~~' $ unalias echo $ type echo echo is a shell builtin $ type -a echo echo is a shell builtin echo is /bin/echo $ echo test test
Here is a function definition that we will discuss:
function cd () { if [[ $1 = "..." ]] then builtin cd ../.. else builtin cd $1 fi }
Discussion
The alias command is smart enough not to go
into an endless loop when you say something like alias ls='ls-a'
or alias echo='echo ~~~'
, so in our first example
we need to do nothing special on the righthand side of our alias
definition to refer to the actual echo
command.
When we have echo defined as an alias, then the type command will tell us not only that this is an alias, but will show us the alias definition. Similarly with function definitions, we would be shown the actual body of the function. ...
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