Linux CLI Commands
Various Linux CLI (Command Line Interface) Commands with examples and grouped by type
File System
check file system size
du
Estimate file space usage
du -hd1 /file_pathlists and summaries directories sizes under /file_path 1 directory deep, where:-dset the reporting depth flag-hset human readable format
du -s /tmp /varlists the summary of directories /var and /tmp only, where:-sset summaries
ncdu
ncdu is a 'smart' version of nu.  It needs to be specifically installed, e.g. sudo apt install ncdu.
- ncdu
 
df
df - report file system space usage
df -hprints file system and spage usage in human readable format
duf
duf - disk usage / Free utility, an updated version of df utility.  It needs to be specifically installed, e.g. sudo apt install duf.
duf
Devices
lshw
Command to list hardware configuration parameters.
sudo lshw -shortlist hardware in short form.sudo lshw -c cpulists the cpu hardware, the following device types can be listed- system
 - bridge
 - memory
 - processor
 - address
 - storage
 - disk
 - tape
 - bus
 - network
 - display
 - input
 - printer
 - multimedia
 - communication
 - power
 - volume
 - generic
 
man
aproposman 5 crontaborman 'crontab(5)'will specifically list the man for contab(5)
crontab
sudo crontab -e can be used to safely