As with many other technologies, VIM can echo messages, if you are coming from a contemporary editor, this can hit differently.
First, the result of all the echoed messages is visible in the status bar at the bottom of the screen,
Secondly, previous messages can be accessed with the :message command.
To echo a message, enter the command mode (ESC or CTRL-C), then type the below command:
:echo "Hello World"
This should print out Hello World to the status bar, but would not preserve the message for later reference.
Echo Commands
There are various echoing forms, each with its unique use case.
Echoing like a comment
The form of echoing demonstrated above is meant for unpreserved echo messages,
The :echon {expr} command is a better form of it.
:echon "This is a comment message"
Highlighting echo results
For some reason you might wish to highlight the result of the echo command, the :echoh or :echohl command makes it possible.
:echoh WarningMsg | echo "Don't panic!" | echo None
The WarningMsg is a type of highlight, another possible highlight can be viewed with the :highlight command
It is required to :echo None at the end or later when the highlighting process is complete.
This preserves the echo messages’ default (None) state.
To provide your custom color, use the highlight command to create a highlight:
:highlight MyGreen ctermfg=green guifg=#00FF00
Use it like the below:
:echoh MyGreen | echo "Green Message" | echo None
Echoing Error Messages
The :echoe {expr} or :echoerr {expr} command can be used to echo error messages
:echoerr "EOL in the current file"
The final message is preserved in the message log.
Saving the result of the echo command
The echom {expr} or echomsg {expr} can be used for messages that should be preserved in the messages log
:echom "Preserved"
To view previously saved messages, use :messages command
Echoing to a window
For some echo messages that can be too long for the status bar, the echow or :echowindow command can be used.
:echow "Lorem Ipsum"
Echoing to a console
echoc can be used to write to the console, although it behaves more like echom when not in GUI mode.
If running as a GUI, the message is output to stdout.
:echoc "what are we doing today?"
VIM’s echo command and Shell’s echo command
It can be tempting to think the VIM’s :echo command is the same as the shell’s !echo command.
One subtle difference is how they both handle the values that they receive.
The :echo command requires Vim native expressions for example to get the current filename do:
:echo expand("%")
Notice that the expand is a Vim expression command that expands some special characters to some values, in this case, the “%” is expanded to the current filename
To have this same result in a shell command, for example, echo the content of the current file
!echo %
The % is replaced with the current filename, this can be useful in other cases e.g. cat the current filename.
Notice how the expand function is not required to get the desired result.
When using the echo command, use vim’s native function for expansion and special effects, in the bash mode, the special characters are expanded before the command is executed.
Namaste!