Difference between revisions of "Disable clearing of boot messages"

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m (Have boot messages stay on tty1: better formatting)
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[[Category:Boot process]]
#REDIRECT [[General troubleshooting#Console messages]]
[[es:Disable Clearing of Boot Messages]]
[[fr:Messages au demarrage]]
{{Article summary start|Summary}}
{{Article summary text|Preventing the boot sequence printout from disappearing.}}
{{Article summary heading|Related}}
{{Article summary wiki|Arch Boot Process}}
{{Article summary end}}
After the boot process, the screen is cleared and the login prompt appears, leaving users unable to read init output and error messages. This default behavior may be modified using methods outlined in this article.
Note that regardless of the chosen option, kernel messages can be displayed for inspection after booting by using {{ic|dmesg}} or all logs from the current boot with {{ic|journalctl -b}}.
== Using flow control ==
This is basic management that applies to most terminal emulators, including virtual consoles (vc):
* Press {{ic|Ctrl+S}} to pause the output
* And {{ic|Ctrl+Q}} to resume it
{{Note|This pauses not only the output, but also programs which try to print to the terminal, since they'll block on the write() calls for as long as the output is paused. If your ''init'' appears frozen, make sure the system console is not paused.}}
== Have boot messages stay on tty1 ==
By default, arch has the {{ic|getty@tty1}} service enabled. The service file already passes {{ic|--noclear}}, which stops agetty from clearing the screen. However [[systemd]] clears the screen before starting it. To disable this behavior edit your getty service file and set
Late KMS starting may still cause the first few boot messages to clear. If this is the case, try enabling [[KMS#Early KMS start|early KMS start]].
There will probably be too many boot messages to view on one screen. Use Shift+PgUp/PgDown to scroll. If there are too many boot messages you still might not be able to see all of them by scrolling. Try increasing the size of your [[Scrollback buffer|scrollback buffer]].
=== Disable clearing in /etc/issue ===
If you have an old {{ic|/etc/issue}} that has the "clear TTY" escape sequences, remove them.
# sed -i $'s/\e\[H//; s/\e\[2J//' /etc/issue

Latest revision as of 21:28, 5 February 2017