Note: iTerm2 provides support for italic text, whereas Apple’s Terminal does not. That’s why this solution discusses only iTerm2.

iTerm 2

1. Enable support for italic text

Preferences > Profiles > Text > Italic text allowed

2. Create TERMINFO entry with italics support

1. Create temporary file terminfo with following content:

    xterm-256color-italic|xterm with 256 colors and italic,
        sitm=\E[3m, ritm=\E[23m,
        use=xterm-256color,
   

2. Create a new entry in the TERMINFO database

    tic terminfo
   

3. Delete the temporary terminfo file

3. Bind iTerm2 to new TERMINFO entry

Preferences > Profiles > Terminal > Report Terminal Type: > xterm-256color-italic

4. Test it

Close and reopen iTerm2, then try:

echo `tput sitm`italics`tput ritm`

If the output is printed in italicised, then iTerm2 is now capable of printing italic text. Furthermore:

echo $TERM

should now output xterm-256color-italic

Sources

• https://gist.github.com/sos4nt/3187620
• https://alexpearce.me/2014/05/italics-in-iterm2-vim-tmux/

Tmux

After italic text is enabled in iTerm2, it works in iTerm2, but not in tmux. This is because tmux uses a different TERM than the terminal in which it is running. To enable italic text in tmux as well, do the following.

1. Create a new TERMINFO entry

1. Create temporary file terminfo with following content:

    tmux|tmux terminal multiplexer,
        ritm=\E[23m, rmso=\E[27m, sitm=\E[3m, smso=\E[7m, Ms@,
        use=xterm, use=screen,
   
    tmux-256color|tmux with 256 colors,
        use=xterm-256color, use=tmux,
   

2. Create new entry in the TERMINFO database:

    tic -x terminfo
   

3. Delete the temporary terminfo file

2. Bind tmux to new TERMINFO entry

Set the following in ~/.tmux.conf:

set -g default-terminal "tmux-256color"
set -as terminal-overrides ',xterm*:sitm=\E[3m'

3. Test it

Close and reopen tmux, then try:

echo `tput sitm`italics`tput ritm`

If the output is printed in italicised, then tmux is now capable of printing italic text. Furthermore:

echo $TERM

should now output tmux-256color

Sources

• https://www.bountysource.com/issues/36925710-tic-can-t-open-when-trying-to-enable-italics-according-to-faq
• http://apple.stackexchange.com/a/249385

Caveat

If using ssh, then the value of the TERM variable is imposed onto the remote system, which many not have it in its database. To fix this problem, we can put the following into ~/.bashrc:

alias ssh="TERM=xterm-256color ssh"