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Table of Contents
Useful commands
Error investigation
Show error and warning messages:
dmesg –level=err,warn
Data management
File and directory size
# du -sh /var/*
Disk usage
Show disk usage with human readable values
# df -h
Show disk INODE usage
# df -1
Change permissions
Change directories permission:
$ find /path/to/base/dir -type d -exec chmod 755 {} +
Change files permission:
$ find /path/to/base/dir -type f -exec chmod 644 {} +
Change ownership
Owner:
$ chown owner_name * -R
Group:
$ chgrp group_name * -R
Copy / backup large folders
Test the command with -n
$ rsync -nav –delete-after /source/ /destination/
Execute command : -a for archive (keep files structure + recursive…), -v for verbose, –delete-after to delete files in backup directory if they do not exist in source (moved, renamed, …)
$ rsync -av –delete-after /source/ /destination/
User management
Users
Create user:
$ sudo useradd -m username
Set password:
$ sudo passwd username
Groups
Create group:
$ sudo addgroup goupname
Config file:
/etc/group
Add user to group:
$ sudo usermod -a -G groupname username
Packages
List installed packages:
sudo apt list –installed
