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Midnight Commander User Menu

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Introduction

One of the most interesting innovation of Orthodox file managers was so called user menu. It is similar to Windows Start button which was created ten years later but still it is more flexible because items that are displayed in it depends on the current context in active panel (type of the current file, the presence of highlighted files in the current  panel, etc). MC user menu items rely on macrovariables to provide context of the operation performed and knowledge of the most common MC Macro Variables  is a prerequisite to constructing you own use menu items.

The user menu is a file with a set of useful actions that can be customized by the user. The current menu in mc is stale and did not change for years. Many items present have no value to the current generation of sysadmins.  That contributes to the situation when few people create their own user menu.  But this is a aberration.

Advanced users of mc should have thier own menu.  MC supports three different menues

A menu file consists of one or more entries. Each entry contains:

Lines that start with any symbol different from space or tab are considered entries for the menu that contain hot key  (in order to be able to use it like a hot key, the first character should be a letter or digit). Description after the hot key letter/digit is optional. All the lines that start with a space or a tab are the commands that will be executed when the entry is selected.

The first thing you should do with Midnight Commander use menu is to delete all items that you do not need from the system menu that ships with the mc. After this cleanup   gradually enhance the menu with operation that you use often and that can benefit from macros such as the current file (%f) the current and passive directory ($d and $D), etc

The first thing you should do with Midnight Commander use menu is to delete all items that you do not need from the system menu that ships with the mc. leave only items that you consider useful.  After that gradually enhance the menu with operation that you use often  and that can benefir from macros suchas the current file(%f) the current and passive directory ($d and $D), etc

For a typical sysadmin more then 50% entries in supplied Midnight Commander user menu are junk and should be deleted.

The structure of the user menu

The format of the menu file is very simple: items are separated with the blank line(s) and consist of blocks of indented line with a header:

Let's look into a simple example:

i   Display ipconfig information
    ifconfig -a

I   Display ipconfig man page
    man ifconfig 

In this case we see two menu items with headers consisting of a single like and containing no visibility predicates. That means that those items will always be displayed in the menu.  You can use macrovariables as ordinary shell variables

X Extract the contents of a compressed tar file
      tar xzvf %f

Here is a more interesting example that uses %D macrosymbol: 

J Copy current directory to other panel recursively 
      tar cf - . | (cd %D && tar xvpf -) 

The menu can also contains comment blocks that are started with '#'. The additional comment lines must start  space or tab.  That permit temporary deletion of the items from the menu

This is essentially the functionality similar to Windows Start menu. Although it was invented before Windows (in 1986 with version 1.p0 of Norton Commander it is more flexible as entries are arbitrary scripts..  But what makes is far superior is visibility predicated and ability to use macrovariables. With visibility predicates instead of one static menu MC users set a set of different menues depending of context exisating in the panel. For example if the panel does not conatin selected files all entries related to this context will be excluded.

The ability to overwrite global entries with more specialized entries

As we mentioned above mc has the  ability to overwrite more global entries with more local, specialized entries.  When the user presses F2, mc checks in three places to find a menu,. The first found menu is used:

  1. Directory menu. First mc checks for the existence of the file .mc.menu in the current directory. It is used if and only if it is owned by the current user or root and is not world-writable.
  2. User menu. Second the existence of the file ~/.mc.menu is checked. the same ownership and permission check as in previous case is performed. used.
  3. System menu After then mc checks so called system menu (the default menu) at  /etc/mc/mc.menu  (older version of mc have a different location) which is always present. This menu is created during the mc installation and can and should be modified by the user to suit his/her needs.

The fact that mc checks for ownership and rights provide the possibility dynamically switch from the user menu to system wide menu and back: to hide user menu from the path all you need is just to change permission to 000 or ownership to nobody.

If you do a lot of specialized operations in particular directory it makes perfect sense to create a menu in the current directory. In all other cases you should probably stick to use and system menu.

Let's look into slightly more complicated example:

v     Edit the current file using vim 
       vim %f

= t  t
V     Edit all selected
       vim %t

It is clear that if there are selected files we probably do not need the item that edits a single file and we can both mark with the same hotkey "v". 

Visibility Conditions

Visibility conditions (or simply conditions) is a method of hiding "irrelevant" items from the user menu invented and implemented in Midnight Commander. The current implementation is ad hoc, but possibly can be reworked and in future based on LUA or some other macro language with standard library.

For example, if particular menu item works only with selected files on active panel, there is a capability to hide this element in "displayed user menu" (which is dynamic and is subset of items defined in user menu) when no selected files in present on active panel.  And if particular element of the panel works only with tar and gtz archive, it is possible to specify that it is excluded if the current file does not have a suitable extension. In way this is a generalization of extensions menu to each item of the user menu.  

MC  "visibility conditions" should preceded the line that specifes the hotkey. Condition starts with single special character.

You can combine default and addition conditions by starting condition with += or =+ (or +=? or =+? if you want debug trace). If you want to use two different conditions, one for adding and another for defaulting, you can precede a menu entry with two condition lines, one starting with + and another starting with =

Conditions syntax

Condition syntax:
  <cond>          = <sub-cond>
  or:		  = <cond> | <cond> ...
  or:		  = <cond> & <cond> ...

Sub-condition is one of following:

f <pattern>	current file matching pattern
F <pattern>	other file matching pattern
d <pattern>	current directory matching pattern
D <pattern>	other directory matching pattern
t <type>	current file of type
T <type>	other file of type
! <sub-cond>	negate the result of sub-condition

Pattern is a normal shell pattern (basic regular expressions). You can override the global value of the shell patterns option by writing shell_patterns=x on the first line of the menu file (where "x" is either 0 or 1).

Type is one or more of the following characters:

For example rlf means either regular file, link or fifo. The t type is a little special because it acts on the panel instead of the file. The condition t t is true if there are tagged files in the current panel and false if not.

If the condition starts with =? instead of = a debug trace will be shown whenever the value of the condition is calculated.

The conditions are calculated from left to right. This means

= f *.tar.gz | f *.tgz & t n
is calculated as
( (f *.tar.gz) | (f *.tgz) ) & (t n)

Here is previous example reworks to use conditions. Note that we use negation of the condition "presence of tagged file" in the second menu entry.

shell_patterns=0

+ t t
V     Edit all selected
      vim %t

+ ! t t
v     Edit the current file (type file)  
      vim %f

Here is another, more complex example of the use of conditions:

= f *.tar.gz | f *.tgz & t n
L	List the contents of a compressed tar-archive
	gzip -cd %f | tar xvf -

Visibility predicates blocks

You can program a series of conditions like a construct that resembles a case statement in shell. We will call this construct "visibility predicate block". The block consists of the main condition (that is specified with = sign) and one of more (often applicable only to files with the extensions specified in the main visibility predicate) sub conditions specified with "+" sign. If the main condition is false all menu items with sub conditions are skipped. If it is true than each sub condition is evaluated in addition to the main visibility predicate and if it is true the menu item is included in the menu. 

The typical usage is to distinguish between cases when there are selected files on the panel and cases when there is no such files.

Here is example of  mc.menu with  default visibility condition that specify several type of file that are processed in subsequent menu items.

= f \.pl | f \.sh | f \.ksh | f ^\.
+ t r & ! t t
5       prettyprint
        case %f in
	  *.pl perl -d %f;;
	  *.sh python bashlint     D="`basename %f .tgz`";;
	  *.tcl)    D="`basename %f .tpz`";;
	  *.sh)  D="`basename %f .tar.Z`";;
	  *.ksh)  D="`basename %f .tar.z`";;
	  *.tar.bz2) D="`basename %f .tar.bz2`"; set bunzip2 -c ;;
	  *.tar.F) D="`basename %f .tar.F`"; set freeze -dc;
	esac
6       check syntax
        case %f in
	  *.pl perl -c %f;;
	  *.sh python bashlint     D="`basename %f .tgz`";;
	  *.tcl)    D="`basename %f .tpz`";;
	  *.sh)  D="`basename %f .tar.Z`";;
	  *.ksh)  D="`basename %f .tar.z`";;
	  *.tar.bz2) D="`basename %f .tar.bz2`"; set bunzip2 -c ;;
	  *.tar.F) D="`basename %f .tar.F`"; set freeze -dc;
	esac

+ t r & ! t t
a       Append file to opposite
    	cat %f >>%D/%f

+ t t
A       Append files to opposite files
    	set %u
    	while [ -n "$1" ]; do
      		cat $1 >>%D/$1 || echo tag $1 >>$MC_CONTROL_FILE
      		shift
    	done

+ t r & ! t t
d       Delete file if a copy exists in the other directory.
    	if [ "%d" = "%D" ]; then
      		echo "The two directores must be different"
      		exit 1
    	fi
    	if [ -f %D/%f ]; then        # if two of them, then
        	if cmp -s %D/%f %f; then
        	    	rm %f && echo %f: DELETED
       		else
        		echo "%f and %D/%f differ: NOT deleted"
            		echo -n "Press RETURN "
            		read key
		fi
    	else
      		echo %f: No copy in %D/%f: NOT deleted.
        fi

+ t t
D       Delete tagged files if a copy exists in the other directory.
    if [ "%d" = "%D" ]; then
      echo "The two directores must be different"
      exit 1
    fi 
        for i in %t
        do 
          if [ -f %D/$i ]; then
            SUM1="`sum $i`"
            SUM2="`sum %D/$i`"
            if [ "$SUM1" = "$SUM2" ]; then
          rm $i && echo ${i}: DELETED
        else
          echo $i and %D/$i differ: NOT deleted.
        fi
      else
        echo %f has no copy in %D/%f: NOT deleted.
          fi
        done

The first sub condition is

+ t r

 That means that the corresponding menu item will be included in the menu if and only if  the current file is a regular file.

The second condition is + t t and means that one or several selected files exists in the active panel. In this case we will perform operation of the selected files instead of the current file.


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NEWS CONTENTS

Old News ;-)

[Aug 20, 2019] Is it possible to insert separator in midnight commander menu?

Jun 07, 2010 | superuser.com

Ask Question Asked 9 years, 2 months ago Active 7 years, 10 months ago Viewed 363 times 2

okutane ,Jun 7, 2010 at 3:36

I want to insert some items into mc menu (which is opened by F2) grouped together. Is it possible to insert some sort of separator before them or put them into some submenu?
Probably, not.
The format of the menu file is very simple. Lines that start with anything but
space or tab are considered entries for the menu (in order to be able to use
it like a hot key, the first character should be a letter). All the lines that
start with a space or a tab are the commands that will be executed when the
entry is selected.

But MC allows you to make multiple menu entries with same shortcut and title, so you can make a menu entry that looks like separator and does nothing, like:

a hello
  echo world
- --------
b world
  echo hello
- --------
c superuser
  ls /

This will look like:

[Aug 19, 2019] mc - Is there are any documentation about user-defined menu in midnight-commander - Unix Linux Stack Exchange

Aug 19, 2019 | unix.stackexchange.com

Is there are any documentation about user-defined menu in midnight-commander? Ask Question Asked 5 years, 2 months ago Active 1 year, 2 months ago Viewed 3k times 6 2


login ,Jun 11, 2014 at 13:13

I'd like to create my own user-defined menu for mc ( menu file). I see some lines like
+ t r & ! t t

or

+ t t

What does it mean?

goldilocks ,Jun 11, 2014 at 13:35

It is documented in the help, the node is "Edit Menu File" under "Command Menu"; if you scroll down you should find "Addition Conditions":

If the condition begins with '+' (or '+?') instead of '=' (or '=?') it is an addition condition. If the condition is true the menu entry will be included in the menu. If the condition is false the menu entry will not be included in the menu.

This is preceded by "Default conditions" (the = condition), which determine which entry will be highlighted as the default choice when the menu appears. Anyway, by way of example:

+ t r & ! t t

t r means if this is a regular file ("t(ype) r"), and ! t t means if the file has not been tagged in the interface.

Jarek

On top what has been written above, this page can be browsed in the Internet, when searching for man pages, e.g.: https://www.systutorials.com/docs/linux/man/1-mc/

Search for "Menu File Edit" .

Best regards, Jarek

[Aug 19, 2019] LinuxCommand.org Midnight Commander

Menu File Format

Some parts of the user menu file format are pretty simple; other parts, not so much. We'll start with the simple parts first.

A menu file consists of one or more entries. Each entry contains:

Here is an example user menu entry that creates an HTML template in the current directory:

# Create a new HTML file

H   Create a new HTML file
    { echo "<html>"
    echo "\t<head>\n\t</head>"
    echo "\t<body>\n\t</body>"
    echo "</html>"; }  > new_page.html

Notice the absence of the -e option on the echo commands used in this example. Normally, the -e option is required to interpret the backslash escape sequences like \t and \n. The reason they are omitted here is that Midnight Commander does not use bash as the shell when it executes user menu commands. It uses sh instead. Different distributions use different shell programs to emulate sh . For example, Red Hat-based distributions use bash but Debian-based distributions like Ubuntu and Raspian use dash instead. dash is a compact shell program that is sh compatible but lacks many of the features found in bash. The dash man page describes the features of that shell.

This command will reveal which program is actually providing the sh emulation (i.e., is symbolically linked to sh):

me@linuxbox ~ $ ls -l /bin/sh

[Aug 10, 2019] Midnight Commander (mc) convenient hard links creation from user menu "

Notable quotes:
"... You can create hard links and symbolic links using C-x l and C-x s keyboard shortcuts. However, these two shortcuts invoke two completely different dialogs. ..."
"... he had also uploaded a sample mc user menu script ( local copy ), which works wonderfully! ..."
Dec 03, 2015 | bogdan.org.ua

Midnight Commander (mc): convenient hard links creation from user menu

3rd December 2015

Midnight Commander is a convenient two-panel file manager with tons of features.

You can create hard links and symbolic links using C-x l and C-x s keyboard shortcuts. However, these two shortcuts invoke two completely different dialogs.

While for C-x s you get 2 pre-populated fields (path to the existing file, and path to the link – which is pre-populated with your opposite file panel path plus the name of the file under cursor; simply try it to see what I mean), for C-x l you only get 1 empty field: path of the hard link to create for a file under cursor. Symlink's behaviour would be much more convenient

Fortunately, a good man called Wiseman1024 created a feature request in the MC's bug tracker 6 years ago. Not only had he done so, but he had also uploaded a sample mc user menu script ( local copy ), which works wonderfully! You can select multiple files, then F2 l (lower-case L), and hard-links to your selected files (or a file under cursor) will be created in the opposite file panel. Great, thank you Wiseman1024 !

Word of warning: you must know what hard links are and what their limitations are before using this menu script. You also must check and understand the user menu code before adding it to your mc (by F9 C m u , and then pasting the script from the file).

Word of hope: 4 years ago Wiseman's feature request was assigned to Future Releases version, so a more convenient C-x l will (sooner or later) become the part of mc. Hopefully

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Last modified: August 19, 2019