Some Linux commands seldom used - so sometimes not remembered

Some tipp 'n tricks to handle you linux system in seldom situations

Tipps I found with variable usefullness:

blockdev --rereadpt /dev/sda7

(from VMWare Communities)

partprobe /dev/sdX

hdparm -z /dev/sda

sfdisk -R /dev/sda

echo 1 > /sys/block/sdX/device/rescan

echo "scsi remove-single-device X X X X" > /proc/scsi/scsi
echo "scsi add-single-device X X X X"    > /proc/scsi/scsi

(X X X X is <AdapterNo.> <Channel> <Id> <LUN>)

echo "- - -" > /sys/class/scsi_host/host<N>/scan

(see Linux Journal)

echo "scsi scsi-scan-devices" > /proc/scsi/scsi

partprobe [options]

(Thanks to linux-poweredge)

sfdisk -R

echo "repair" > /sys/block/md127/md/sync_action

Credits: Superuser: how to force mdadm to sync to device after raid6 repair and how to get number of errors?

In case you are in danger, that your remote system might hang while doing a clean shutdown, a “cold reboot” triggered by software might help

echo b > /proc/sysrq-trigger

Credits and further reading: GEEX, ct' online, kernel.org git.kernel.org

Regain access to an build-in card reader after

udisksctl power-off -b /dev/sdc

/var/log/syslog

Feb 26 16:38:27 myhost udisksd[6074]: Ignoring SCSI command START STOP UNIT failure (Non-GOOD SCSI status from SGIO v3 ioctl: status=2 host_status=0 driver_status=8) on /dev/sdc
Feb 26 16:38:27 myhost udisksd[6074]: Powered off /dev/sdc - successfully wrote to sysfs path /sys/devices/pci0000:00/0000:00:1d.7/usb2/2-4/remove
Feb 26 16:38:27 myhost kernel: [179303.432273] usb 2-4: USB disconnect, device number 8
Feb 26 16:38:27 myhost colord: device removed: sysfs-HP-HP_Flash_Media_Reader
Feb 26 16:38:28 myhost colord-sane: io/hpmud/pp.c 627: unable to read device-id ret=-1

succeeded with:

echo 0 > /sys/bus/usb/drivers/usb/usb2/authorized
echo 1 > /sys/bus/usb/drivers/usb/usb2/authorized

Credits: How do you reset a USB Device from the command line? - Ask Ubuntu

Entries: systemd, hibernate

/etc/systemd/sleep.conf.diff

diff -u -r1.1 sleep.conf
--- sleep.conf  2020-04-01 19:23:42+02  1.1
+++ sleep.conf  2022-10-07 10:19:04+02
@@ -18,7 +18,7 @@
 #AllowHybridSleep=yes
 #SuspendMode=
 #SuspendState=mem standby freeze
-#HibernateMode=platform shutdown
+HibernateMode=shutdown
 #HibernateState=disk
 #HybridSleepMode=suspend platform shutdown
 #HybridSleepState=disk

References:

• https://www.freedesktop.org/software/systemd/man/systemd-sleep.conf.html