# What does “rm is hashed” mean?

I'm going through http://mywiki.wooledge.org/BashGuide/CommandsAndArguments and came across this:

$type rm rm is hashed (/bin/rm)$ type cd
cd is a shell builtin


Just a little earlier, the guide listed the various types of commands understood by Bash: aliases, functions, builtins, keywords and executables. But there wasn't mention of "hashed". So, in this context, what does "hashed" mean?

It's a performance thing; instead of searching the whole path for the binary every time it is called, it's put into a hash table for quicker lookup. So any binary that's already in this hash table, is hashed. If you move binaries around when they're already hashed, it will still try to call them in their old location.

See also help hash, or man bash and search for hash under builtin commands there.

As others have mentioned the hash is a associative array (key --> value) that Bash maintains so that when a command is executed, Bash searches this hash first to see if the command's location on disk has already been found via $PATH, and stored there for quicker searching. You can preload the hash by giving a list of commands that you want Bash to find when it's invoked. This variable is called BASH_CMDS. excerpt from man page  BASH_CMDS An associative array variable whose members correspond to the internal hash table of commands as maintained by the hash builtin. Elements added to this array appear in the hash table; unsetting array elements cause commands to be removed from the hash table.  Additionally if you look at the Bash man page there is a section titled, COMMAND EXECUTION which details the state machine that Bash uses when a command is typed at the prompt. excerpt  If the name is neither a shell function nor a builtin, and contains no slashes, bash searches each element of the PATH for a directory con‐ taining an executable file by that name. Bash uses a hash table to remember the full pathnames of executable files (see hash under SHELL BUILTIN COMMANDS below). A full search of the directories in PATH is performed only if the command is not found in the hash table. If the search is unsuccessful, the shell searches for a defined shell function named command_not_found_handle. If that function exists, it is invoked with the original command and the original command's arguments as its arguments, and the function's exit status becomes the exit status of the shell. If that function is not defined, the shell prints an error message and returns an exit status of 127.  You can find out what's currently in your hash using the -l switch. ### Example $ hash -l
builtin hash -p /usr/bin/rm rm
builtin hash -p /usr/bin/sudo sudo
builtin hash -p /usr/bin/man man
builtin hash -p /usr/bin/ls ls

• very helpful thank you. While I'm working on a script I find this hash thing gets in the way. Is there a way to disable or clear this? – qodeninja Aug 23 '19 at 17:18

hash is a Bash shell built-in that provides hashing for commands.

hash [-lr] [-p filename] [-dt] [name]


Straight from the horse's mouth:

help hash

Remember or display program locations.

info Bash → Shell Builtin Commands → Bourne Shell Builtins

Remember the full pathnames of commands specified as NAME arguments, so they need not be searched for on subsequent invocations. The commands are found by searching through the directories listed in \$PATH. The -p option inhibits the path search, and FILENAME is used as the location of NAME. The -r option causes the shell to forget all remembered locations. The -d option causes the shell to forget the remembered location of each NAME. If the -t option is supplied, the full pathname to which each NAME corresponds is printed. If multiple NAME arguments are supplied with -t the NAME is printed before the hashed full pathname. The -l option causes output to be displayed in a format that may be reused as input. If no arguments are given, or if only -l is supplied, information about remembered commands is printed. The return status is zero unless a NAME is not found or an invalid option is supplied.