Linux CLI Commands

Various Linux CLI (Command Line Interface) Commands with examples and grouped by type

• Using ls:
  • ls -lhaF | grep ^l # list links
  • ls -lhaF | grep ^d # list directories
  • ls -lhaF | grep ^- # list files

• using find:
  • find . -type l -ls
  • find . -maxdepth 1 -type l -ls to process the current directory only, i.e. not recurse.

References:

• How to list all symbolic links in a directory
• Why you shouldn't parse the output of ls(1)

Estimate file space usage

• du -hd1 /file_path lists and summaries directories sizes under /file_path 1 directory deep, where:
  • -d set the reporting depth flag
  • -h set human readable format
• du -s /tmp /var lists the summary of directories /var and /tmp only, where:
  • -s set summaries
• sudo du -hd1 --exclude={/mnt,/run,/proc} / to check root (/).
  • It is important to exclude the noted directories as they are temporary or external drives. Note I mount my external drives within /mnt. This speed up performance and remove errors and associated messages, decluttering the output.

ncdu is a 'smart' version of du. It needs to be specifically installed, e.g. sudo apt install ncdu.

• ncdu on the current directory
• ncdu --exclude-kernfs --exclude /mnt / to check root (/) directory excluding system and mounts

df - report file system space usage

• df -h prints file system and spage usage in human readable format

duf - disk usage / Free utility, an updated version of df utility. It needs to be specifically installed, e.g. sudo apt install duf.

• duf

Command to list hardware configuration parameters.

• sudo lshw -short list hardware in short form.
• sudo lshw -c cpu lists 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

• apropos
• man 5 crontab or man 'crontab(5)' will specifically list the man for contab(5)

sudo crontab -e can be used to safely