Linux shell/Commands

One liners

df -h   #displays filesystem disk space usage for all mounted partitions
du -skh * | sort -n #displays the disk usage summary for each directory 
free -m   #displays the amount of free and used memory in the system
lsb_release -a #prints version information for the Linux release you're running
tload -draws   #system load on text based graph

Copy with progress bar

rsync and cp

• rsync -aP - copy with progress can be also aliased alias cp='rsync -aP'
• cp -rv old-directory new-directory - shows progress bar

PV does not preserve permissions and does not handle attributes

• pv ~/kali.iso | cat - /media/usb/kali.iso equals cp ~/kali.iso /media/usb/kali.iso
• pv ~/kali.iso > /media/usb/kali.iso equals cp ~/kali.iso /media/usb/kali.iso
• pv access.log | gzip > access.log.gz shows gzip compressing progress.

PV can be imagined as CAT command piping '|' output to another command with a bar progress and ETA times. -c makes sure one pv output is not use to write over to another, -N creates a named stream. Find more at How to use PV pipe viewer to add progress bar to cp, tar, etc..

$ pv -cN source access.log | gzip | pv -cN gzip > access.log.gz
source:  760MB 0:00:15 [37.4MB/s] [=>     ] 19% ETA 0:01:02
gzip: 34.5MB 0:00:15 [1.74MB/s] [  <=>  ]

Tail log files

tail-f-the-output-of-dmesg or install multitail

• tail -f /var/log/{messages,kernel,dmesg,syslog} - old school but not perfect
• watch 'dmesg | tail -50' - approved by man dmesg
• watch 'sudo dmesg -c >> /tmp/dmesg.log; tail -n 40 /tmp/dmesg.log' - tested, but experimental

Replace unix timestamps in logs to human readable date format

user@laptop:/var/log$ tail dmesg | perl -pe 's/(\d+)/localtime($1)/e'
[   Thu Jan  1 01:00:29 1970.168088] b43-phy0: Radio hardware status changed to DISABLED
[   Thu Jan  1 01:00:29 1970.308597] tg3 0000:09:00.0: irq 44 for MSI/MSI-X
[   Thu Jan  1 01:00:29 1970.344378] IPv6: ADDRCONF(NETDEV_UP): eth0: link is not ready
[   Thu Jan  1 01:00:29 1970.344745] IPv6: ADDRCONF(NETDEV_UP): eth0: link is not ready
 
user@laptop:/var/log$ tail dmesg
[   29.168088] b43-phy0: Radio hardware status changed to DISABLED
[   29.308597] tg3 0000:09:00.0: irq 44 for MSI/MSI-X
[   29.344378] IPv6: ADDRCONF(NETDEV_UP): eth0: link is not ready
[   29.344745] IPv6: ADDRCONF(NETDEV_UP): eth0: link is not ready

References

• Transforming Unix Timestamps in logs to date

Useful packages

• ARandR Screen Layout Editor - 0.1.7.1

Copy and Paste in terminal

In Linux X graphical interface this works different then in Windows you can read more in X Selections, Cut Buffers, and Kill Rings. When you select some text this becomes the Primary selection (not the Clipboard selection) then Primary selection can be pasted using the middle mouse button. Note however that if you close the application offering the selection, in your case the terminal, the selection is essentially "lost".

Option 1 works in X

• select text to copy then use your mouse middle button or press a wheel

Option 2 works in Gnome Terminal

• Ctrl+Shift+C -to copy
• Ctrl+Shift+V or Shift+Insert -to paste

Option 3 Install Parcellite GTK+ clipboard manager

sudo apt-get install parcellite

then in the settings check "use primary" and "synchronize clipboards"

Generate random password

cat /dev/urandom|tr -dc "a-zA-Z0-9"|fold -w 48|head -n1

Localization

Change a keyboard layout

setxkbmap gb