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back | nextKill idle TTYs
Here is a simple shell script to kill terminals that have been idle for a long time. You can identify such sessions in the IDLE column of the Linux
w command. This corresponds to the last modified date of the respective TTY device file.$ w 10:56:54 up 10 days, 23:54, 7 users, load average: 1.17, 1.10, 1.16 USER TTY LOGIN@ IDLE JCPU PCPU WHAT aron pts/0 10:56 1.00s 0.01s 0.01s w betty pts/4 Mi10 22:25m 0.02s 0.00s tail -F error.log cher pts/5 06:32 4:16m 0.04s 0.04s -bash dave pts/8 09:56 41:02 0.06s 0.05s vim config erin pts/9 08:26 2:26m 0.03s 0.03s -bash fritz pts/12 09:30 1:25m 0.03s 0.02s git server greg pts/13 10:47 9:26 0.32s 0.32s less +F -S --follow-name /var/log/messages
kill-idle:
#!/bin/bash
# Sends SIGHUP to TTYs which are idle for a defined time.
# Default is 8 hours.
# Syntax: kill-idle [idle-hours]
LIMIT=${1:-8}
T=$(mktemp)
NOW=$(stat -t "${T}" | awk '{ print $12}')
[ -z ${NOW} ] && exit 1
cd /dev
for TTY in pts/*; do
if [ "${TTY}" = "pts/ptmx" ]; then
continue
fi
# field 12 is "last access" which is the time of last write to the tty (last keypress)
MOD=$(stat -t "${TTY}" | awk '{ print $12}')
let AGO=$((NOW - MOD))
if [ ${AGO} -gt $((LIMIT*3600)) ]; then
pkill -HUP -t "${TTY}"
fi
done
rm "${T}"
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Fix Eclipse wide fonts
If fonts in Eclipse and other GTK UI on Linux look too wide or too high or have too much padding around them, then check your GTK font settings! Using a different font may give you a much better layout.
Especially DejaVu Sans and Liberation Sans have a much lower height than Noto Sans for example.
~/.config/gtk-3.0/settings.ini:
Especially DejaVu Sans and Liberation Sans have a much lower height than Noto Sans for example.
~/.config/gtk-3.0/settings.ini:
gtk-font-name=Liberation Sans, 10
Make very sure Oracle uses async IO on Linux
A default installation of Oracle on Linux will use synchronous IO. You have to explicitly enable asynchronous IO by setting a parameter (sic!):
and restart Oracle. If you don't do that then synchronous IO during logfile switches / checkpoints will cause unnecessary waits: log file switch (checkpoint incomplete). At the same time Oracle DBW process will not saturate IO. Your DB will become barely usable during those times.
ALTER SYSTEM SET FILESYSTEMIO_OPTIONS=SETALL SCOPE=SPFILE;and restart Oracle. If you don't do that then synchronous IO during logfile switches / checkpoints will cause unnecessary waits: log file switch (checkpoint incomplete). At the same time Oracle DBW process will not saturate IO. Your DB will become barely usable during those times.
As this also enables direct writes (which circumvent the OS page cache) you must also ensure that the SGA size is close to the RAM size (70-80%). Do not enable the parameter above for small SGAs (< 4GB).
package.keywords becomes package.accept_keywords
As of
sys-apps/portage-2.3.89 Gentoo installations must rename /etc/portage/package.keywords to /etc/portage/package.accept_keywords.Relaying SIGINT signal to child processes
Here is a bash function (plus test program) that correctly relays important signals to child processes. So that pressing Ctrl-C reliably terminates both all child processes and the parent process.
- Delivers interrrupt signals also to parent process again (after removing signal handler)
- SIGPIPE is only sent to children
- Works for any number of child processes
- Does not work for SIGKILL (no signal is delivered to app in that case)
#!/bin/bash
relay() {
PIDS=""
for PID in $(pgrep -P $$); do
PIDS="${PIDS} ${PID}"
done
trap "kill -PIPE ${PIDS}" PIPE
PIDS="${PIDS} $$"
#echo "setting up traps to ${PIDS}"
trap "trap - HUP; kill -HUP ${PIDS}" HUP
trap "trap - INT; kill -INT ${PIDS}" INT
trap "trap - QUIT; kill -QUIT ${PIDS}" QUIT
trap "trap - TERM; kill -TERM ${PIDS}" TERM
}
(sleep 10; echo '1st subshell was not killed')&
relay $!
(sleep 10; echo '2nd subshell was not killed')&
relay $!
echo 'please hit Ctrl-C within 10s'
sleep 10
wait
echo 'main shell was not killed'
Fix Firefox Password suggestions
If you have many saved passwords in Firefox's Password Manager then the password suggestions on login forms can become unusably long.
To restore the previous behaviour, in about:config set
To restore the previous behaviour, in about:config set
signon.includeOtherSubdomainsInLookup to false.linux-5.5 mm looks very good
My tests with the upcoming Linux kernel are looking very promising. For me memory management issue has been improved a lot. In recent 5.x kernels the mm would trigger a lot of reclaim scans even with low memory pressure. For example on a 2GB laptop the Normal zone is quite small. Most memory is in the DMA32 zone. And those kernels would trigger reclaim and even swap when opening a browser or using gitk on the kernel repo. Even though there is still plenty of usable RAM.
With 5.5 this is resolved. Reclaim scans are rare again and swap is not used in these situations.
With 5.5 this is resolved. Reclaim scans are rare again and swap is not used in these situations.
Gentoo updating gcc, mpfr, mpc
When Gentoo updates gcc together with mpfr and mpc the normal emerge procedure will cause building of gcc twice. Because mpfr and mpc cause automatic rebuild of the (existing) gcc. But if you are going to update gcc anyway then this is utterly pointless waste of energy.
Instead you can
After gcc update don't forget to switch to the new compiler with
Instead you can
emerge --ignore-built-slot-operator-deps=y -1uav mpfr mpc first without doing the rebuild. This leaves you with a broken gcc maybe (but actually probably not because portage preserves the old library versions), but next you simply emerge -1uav gcc anyway.After gcc update don't forget to switch to the new compiler with
gcc-config and rebuild libtool.Gentoo replacing ntp, vixie-cron, man
Gentoo is cleaning out its closet. It has removed unmaintained upstream packages which were still popular: ntp, vixie-cron and man. Of course it's a logical step and using the modern replacements is rational.
For net-misc/ntp, use net-misc/ntpsec: This has way more robust configuration while eliminating ancient obscure features like traps.
For vixie-cron, use sys-process/cronie. It also itegrates anacron, so you get two in one.
For man, use man-db which is faster as it uses a BDB backend instead of text files.
For net-misc/ntp, use net-misc/ntpsec: This has way more robust configuration while eliminating ancient obscure features like traps.
For vixie-cron, use sys-process/cronie. It also itegrates anacron, so you get two in one.
For man, use man-db which is faster as it uses a BDB backend instead of text files.
Java and its use of filesystem syscalls
File f = new File("build.xml");
// openat(AT_FDCWD, "build.xml", O_RDONLY) = 96
// fstat(96
InputStream io = new FileInputStream(f);
// read(96
io.read();
// read(96
io.read();
// close(96)
io.close();
Path p = f.toPath();
// openat(AT_FDCWD, "build.xml", O_RDONLY) = 96
io = Files.newInputStream(p);
// read(96
io.read();
// read(96
io.read();
// close(96)
io.close();
The NIO way of creating an input stream from a file actually saves an fstat syscall.