Mount disk by UUID in Linux



Example output

/dev/xvdb1: UUID="42fbe9a1-eea1-34bc-439d-19a0b48e7df1" TYPE="xfs"

Mount drive using the UUID

[root@host ~]# mount -U 42fbe9a1-eea1-34bc-439d-19a0b48e7df1 /mnt

Add to fstab to automatically mount on system boot up

vi /etc/fstab

Add the following, swap out the UUID for your devices UUID

UUID="42fbe9a1-eea1-34bc-439d-19a0b48e7df1" /backup xfs defaults 0 0

Save and exit. Now when the system reboots it should automatically mount the drive. You should also be able to call “mount -a” to automatically mount everything in fstab.

How To Increase Session Timeout for SSH

From the server side, edit the /etc/ssh/sshd_config

Change, uncomment, or add

ClientAliveInterval 120
ClientAliveCountMax 15

Change the AliveInterval and CountMax as desired.

More info on the AliveIntercal and CountMax.

ClientAliveCountMax Sets the number of client alive messages which may be sent without sshd(8) receiving any messages back from the client. If this threshold is reached while client alive messages are being sent, sshd will disconnect the client, terminating the session. It is important to note that the use of client alive messages is very different from TCPKeepAlive. The client alive messages are sent through the encrypted channel and therefore will not be spoofable. The TCP keepalive option enabled by TCPKeepAlive is spoofable. The client alive mechanism is valuable when the client or server depend on knowing when a connection has become unresponsive.

The default value is 3. If ClientAliveInterval is set to 15, and ClientAliveCountMax is left at the default, unresponsive SSH clients will be disconnected after approximately 45 seconds. Setting a zero

ClientAliveCountMax disables connection termination.ClientAliveInterval Sets a timeout interval in seconds after which if no data has been received from the client, sshd(8) will send a message through the encrypted channel to request a response from the client. The default is 0, indicating that these messages will not be sent to the client.

More information

Turn 3.5mm Jack on Raspberry Pi Running LineageOS 16

You will need an Android Terminal. You can turn on the default one in the developer settings. Need to turn on developer mode?

You will also need to enable root which can also be done in the Developer settings

Open up the terminal app and run


More info here

Linux Screen – Create, Connect, Disconnect, Terminate Sessions

Screen is a handy tool that can help you run scripts on servers remotely without having to worry about the session getting terminated. It seems to operate kinda like a virtual console.

Create Screen Session

Create a new session with a specified name

screen -S SessionName

Example output below. Create session named testsession and print screen sessions.

[bob@localhost imapsync]$ screen -S testsession
[bob@localhost imapsync]$ screen -ls
There are screens on:
3313.testsession (Attached)
1 Sockets in /var/run/screen/S-bob.
[bob@localhost imapsync]$

Disconnect from Screen Session

You can disconnect from a screen session by hitting ctrl + a and then ctrl +d

“ctrl + a” then “ctrl + d”

List Screen Sessions

You can list the screen sessions with

screen -ls


[bob@localhost imapsync]$ screen -ls
There are screens on:
3212.testsession (Detached)
2556.xap (Detached)

2 Sockets in /var/run/screen/S-bob.
[bob@localhost imapsync]$

Connect to screen Session

You can reconnect to a screen session with

screen -r testsession 

Terminate Screen Session

To terminate a screen session, connect to that session and then on a clear line hit ctrl + d

Same way as if you were closing a remote ssh connection.

LibreNMS backup script

You should be able to copy and paste the following in a file and then execute from cron. Should work out of the box, but you can change the backup directory and the path if needed/wanted.


# LibreNMS backup script
# Jan 1, 2019

lDate=`date +%Y%m%d-%H%M`       # local date + hour minute
dDate=`date +%Y%m%d`            # todays date

# If you have the script, you can trigger a backup notification
ALERT="/home/admin/ -b"

# Directory to backup to

# MySQL settings for tar and sqldump

# Directory that contains data

# tar LibreNMS dir
# tar SQL dir "the whole thing with the innode files
# sql dump of the db for extra redundancy

if [ -d ${bDir} ]; then
echo "backup dir exist, starting to backup"
        echo "backup dir not available.  Quiting"
        exit 1

${ALERT} "Starting backup for ${bName} - `date`"

systemctl stop mariadb httpd
# LibreNMS data backup
tar -zcvf ${bDir}/${lDate}-${bName}.tgz ${dDir}
if [ $? -eq 0 ]; then
        echo "Tar succesfully backed up ${bDir}"
        echo "Tar failed while trying to backup ${dDir}"
        echo " ${lDate} - Tar failed while trying to backup ${dDir}" >> ${LOG}
        ${ALERT} "${lDate} - Tar failed while trying to backup ${dDir}"

# MySQL data backup
tar -zcvf ${bDir}/${lDate}-${bName}-mysql.tgz ${sqlDir}
if [ $? -eq 0 ]; then
        echo "Tar succesfully backed up ${sqlDir}"
        echo "Tar failed while trying to backup ${sqlDir}"
        echo " ${lDate} - Tar failed while trying to backup ${sqlDir}" >> ${LOG}
        ${ALERT} "${lDate} - Tar failed while trying to backup ${sqlDir}"

systemctl start mariadb httpd
sleep 5

 # SQL dump
mysqldump -u ${sqlUN} -p'4rfvBHU8!' ${sqlDB} > ${bDir}/${lDate}-${bName}.sql
if [ $? -eq 0 ]; then
        echo "MySQL DB dumped"
        echo "Ran into error while doing sql dump"
        echo "${lDate} - Ran into error while doing sql dump" >> ${LOG}
        ${ALERT} "${lDate} - Ran into error while doing sql dump"

echo "Removing old backups"
if ( ls ${bDir} | grep -q ${dDate} );then
        find ${bDir}/* -prune -mtime +31 -exec rm {} \;
        echo "Looks like there are no backup files!  Aborting!!!"
        ${ALERT} "${lDate} - Error: find failed to find any backup files in backup dir.  Aborting!!!"

${ALERT} "Finished backup for ${bName} - `date`"

Ubuntu expand disk space – Command Line

Warning: Be extremely careful when making changes to partitions and disk as it can lead to broken systems and lost data. Make sure you have a backup.

This scenario is done on a basic Ubuntu install. No fancy LVM stuff going on. If you need that, refer to here

Disk /dev/sda: 64 GiB, 68719476736 bytes, 134217728 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disklabel type: dos
Disk identifier: 0x2062ec28
Device     Boot    Start      End  Sectors  Size Id Type
/dev/sda1  *        2048 65011711 65009664   31G 83 Linux
/dev/sda2       65013758 67106815  2093058 1022M  5 Extended
/dev/sda5       65013760 67106815  2093056 1022M 82 Linux swap / Solaris

From the above output of fdisk -l, we see that the disk has 64GiB available, but the primary partition is only 31G. To make the primary partition larger we need to

  • Run fdisk “fdisk /dev/sda”
  • Delete partitions 2 and 5,
  • Delete Partition 1
  • Create Partition 1 again on the same starting boundary
  • Put the end boundary close to the end so we end up with ~62GiB for that partition
  • Recreate sda2, the 1GiB extended partition
  • Write changes to disk
  • Run resize2fs to resize the filesystem

You may need to boot up in recovery to get this command working. Also if you boot up in recovery, you’ll need to remount the root / partition read/write. More info here.

resize2fs /dev/sda1

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