Linux shell/Commands

One liners

• df -h displays filesystem disk space usage for all mounted partitions
• du -sh displays the disk usage for a directory, -s is for summary
• 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] [  <=>  ]

Useful packages

• ARandR Screen Layout Editor - 0.1.7.1

List partitions

lsblk 
NAME   MAJ:MIN RM   SIZE RO TYPE MOUNTPOINT
sda      8:0    0  55.9G  0 disk 
├─sda1   8:1    0  54.4G  0 part /
├─sda2   8:2    0     1K  0 part 
└─sda5   8:5    0   1.5G  0 part [SWAP]

sudo fdisk -l
Disk /dev/sda: 60.0 GB, 60011642880 bytes
255 heads, 63 sectors/track, 7296 cylinders, total 117210240 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x000f12f1

   Device Boot      Start         End      Blocks   Id  System
/dev/sda1   *        2048   114083839    57040896   83  Linux
/dev/sda2       114085886   117209087     1561601    5  Extended
/dev/sda5       114085888   117209087     1561600   82  Linux swap / Solaris

sudo sfdisk -ls
/dev/sda:  58605120

Disk /dev/sda: 7296 cylinders, 255 heads, 63 sectors/track
Warning: extended partition does not start at a cylinder boundary.
DOS and Linux will interpret the contents differently.
Units = cylinders of 8225280 bytes, blocks of 1024 bytes, counting from 0

   Device Boot Start     End   #cyls    #blocks   Id  System
/dev/sda1   *      0+   7101-   7102-  57040896   83  Linux
/dev/sda2       7101+   7295-    195-   1561601    5  Extended
/dev/sda3          0       -       0          0    0  Empty
/dev/sda4          0       -       0          0    0  Empty
/dev/sda5       7101+   7295-    195-   1561600   82  Linux swap / Solaris

• -l : List the partitions of a device.
• -s : List the size of a partition.
• -u or -uS or -uB or -uC or -uM : Accept or report in units of sectors (blocks, cylinders, megabytes, respecpively). The default is cylinders, at least when the geometry is known

Generate random password

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