• dmenu reads stdin, it splits the input based on a separator (newline character) and displays each item as a selectable entry. Confirming the selection will output that item to stdout.
• dmenu also has a input textbox, that is used to filter the input list.
• input can be arbitrary and will be shown on stdout the same way as regular entries.

• it's possible to force output to match stdin. Entries that are not part of stdin are ignored
• each line can have multiple actions, depending on the key that was pressed. rofi will return a different exit code on each key (default: Alt-{1-9} > exit codes 10-18)
• filtering is case insensitive by default.
• rofi can select a certain line number on startup.
• rofi can filter the list with the -filter argument. This will basically put text into input bar and filter the list accordingly
• entries can be colored line by line, it's possible to color ranges and single lines. (x-y and x,y,z)
• formatting of stdout with -format parameter
• -format i will show line number, starting at 0
• -format s will show line content
• -format e will show the line content, shell quoted.
• -format f will show last used filter
• -format F will show last used filter, shell quoted

echo -e "foo\nbar" | rofi -dmenu -format i:s
1:bar

You can get icon with a row by passing extra information in the line like:

echo -en "aap\0icon\x1ffolder\n"

Here:

• \0 indicates end of entry.
• \x1f is the field separator.
• \n is the entry separator.

Currently only 'icon' is supported.

• allow to separate input into a visible output and a hidden string, which matches output.
• allow to output all filtered results to stdout
• mark lines to be printed on stdout
• make certain lines not selectable (think of help text at the top) - this could work similar to -u and -a options