Hints: using script(1) or vidcontrol(1) when scrollback is insufficient

[Cath O'Deray]

With (for example) a virtual terminal such as ttyv1, it's sometimes impossible to see what's required.

A command like this, following a major upgrade to base, might summarise a number of (port) packages to be removed, without allowing you to see the name of any such package:

pkg upgrade --force --repository FreeBSD-ports --quiet --dry-run

Hint​

1. Use script
2. run the required command(s)
3. exit
4. work with the typescript.

Re: the attached screenshots, I need not worry about the removal of postgresql15-client, because

• a superior version of the PostgreSQL client will be installed
• I can see the UPDATING file entry about the switch of the default version of PostgreSQL from 15 to 16.

 

[Kai Burghardt]

Neat use of script(1). I’m nonetheless missing you mentioning the CONS_HISTORY ioctl(2) which you can trigger with vidcontrol(1):​

vidcontrol -h 99999 # 99,999 lines of scroll back buffer

 

[Cath O'Deray]

Oh, vidcontrol is probably much more useful, thanks for the education!

I broadened the subject line.

 

[SirDice]

Also note that terminal multiplexers like tmux(1) and screen(1) have their own scrollback buffers.

 

[T-Aoki]

To scroll back to see kernel outputs on boot, kern.msgbufsize should be increased n*default in /boot/loader.conf.
I have kern.msgbufsize=1146880 in /boot/loader.conf.
For boot time kernel messages (especially for verbose boot), /etc/rc.conf[-local] and/or /etc/sysctl.conf is too late to configure.