This article explains how to enable italic text in iTerm2 and Tmux.

It links to this article which suggests overriding the existing terminfo entry so that ssh uses the correct (new) profile by default. Otherwise you'd need to pass the correct environment along with the SSH command.

iTerm2

Enable support for italic text

Preferences > Profiles > Text > Italic text allowed

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

Bind iTerm2 to new TERMINFO entry

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

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.

Also the below command should now output xterm-256color-italic

echo $TERM

TMUX

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.

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'

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