execute-and-log.zsh

# Write the history entry ourselves, as we empty $BUFFER it won't be written
# by zsh.
zle && [[ $HISTNO -eq $HISTCMD ]] && print -sr -- "$PREBUFFER$BUFFER"

# Save what would have been executed by .accept-line and empty out what zsh
# knows about the command entered.
EXEC=$BUFFER
BUFFER=

zle .accept-line

# Write newline.
echo

# Create a file descriptor that will receive the command output.
exec 9>>/tmp/output.txt

# Write the command that will be executed to the log.
echo $EXEC 1>&9 2>&9

# Write command output to the log.
eval $EXEC 1>/dev/tty 2>/dev/tty 1>&9 2>&9

# Close file descriptor.
exec 9>&-

# Issues:
# - Does not work with interactive programs like vim or git add --patch
# - Due to redirection in line 22 we lose colors for ls and git commands unless
#   git config --get color.ui returns always.