Basic commands
All the commands below are tested under Ubuntu 18.04.5 LTS
To check disk size
$ df -lh
To check specific size of directory
$ du -sh /directory
Potential disk size overflow
If you have systemd service running and with logs, the disk space maybe used up a lot when something wrong going on the service.
You can check the size of syslog
$ du -sh /var/log/syslog*
If there is a very big size syslog, that means most of the disk space usage is caused by the syslog
You can limit the size of log or rotate the log by editing rsyslog located at /etc/logrotate.d/
$ sudo nano /etc/logrotate.d/rsyslog
Example below is to limit to size of 100k and rotate for 7 logs in total
/var/log/syslog
{
rotate 7
size 100k
daily
}
However, this is just a temporary workaround, you should check why which program is generating big size of syslog
Restart the service
$sudo systemctl restart rsyslog.service
Sometimes, the error message from ROS may generate big size of log as well.
You can check using the command
$ cd
$ du -sh .ros/log
To check saved password for Wifi
$ cd /etc/NetworkManager/system-connections
$ sudo cat <saved_network_connection>
Symlink
To create symlink
$ ln -s <path to the file/folder to be linked> <the path of the link to be created>
-s flag means the link is soft, without -s, by default it would be hard link
To remove symlink
$ unlink <path-to-symlink>
or
$ rm <path-to-symlink>
Swap memory
Check swap memory
$ free -m
Clear swap memory
we can cycleoff the swap memory but turn it off and on again
$ sudo swapoff -a
$ sudo swapon -a
Scan ip address of devices
Dependencies
$ sudo apt install nmap
Scan
$ sudo nmap -sn <ip_address>/24 // for example 192.168.10.0/24
Add user to dialout
$ sudo usermod -a -G dialout $USER
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