$ which echo echo: shell built-in command. $ which ls /bin/ls $ which cat /bin/cat Why is echo not an independent utility like ls, ps, cat etc? Why is it shell specific? Any good reasons?
Is there any intrinsic difference between a builtin command and another command which can nominally do the same thing? eg. Do builtins get "special" treatement? ... is there less overhead running ...
I've hacked on a lot of shell scripts, and sometimes the simplest things baffle me. Today I ran across a script that made extensive use of the : (colon) bash builtin. The documenation seems simple ...
Is there anywhere you can download a manpage for every builtin commands? I know you can just use help or man bash and search to find info about it, but I want them separated, so I can just do man ...
how does built in commands of a shell implemented in Linux? as a function or thread of shell process?
I know that external commands are run in the shell by creating a separate process. But what exactly happens when a built in command is run in a shell. Are they executed as a function or if the shell ...
Let's say if I type in cd in my shell. Is cd loaded from the memory at that moment? My intuition is that these built-in commands are pre-loaded to the system memory after the kernel has been loaded, ...
Normally, bash is able to assign multi-line output of a command: L=`ls` This works from both interactive shell and scripts. But it appears the output of a builtin can't be captured in a variable: ...
Running simply builtin prints nothing and returns exit code 0. This is in accordance with help builtin, which shows all parameters as optional. But why isn't this no-op an error? Is there a use case ...
Typing man alias gives me No manual entry for alias The same thing goes for export and eval. At first I thought it only happens to shell built-in commands but man echo gives me the man page. ...