wipefs - it is used to erase various types of signatures from a device
syntax
$ sudo wipefs device_name
To print help options
$ wipefs --help
To obtain the list of all the signatures existing on the /dev/vda1 device
$ sudo wipefs /dev/vda1
To include only the DEVICE, OFFSET and USAGE columns
$ sudo wipefs --output DEVICE,OFFSET,USAGE /dev/vda1
To obtain the output in the JSON format
$ sudo wipefs -J --output DEVICE,OFFSET,USAGE /dev/vda1
To find and erase all the signatures on a device
$ sudo wipefs /dev/vda*
To erase all signatures on /dev/vda
$ sudo wipefs -a /dev/vda*
To make a dry run
$ sudo wipefs -n /dev/vda*
regards,
T.Dhanasekar
whoami - print effective userid
syntax
$ whoami [option]
To show the name of the currently logged-in user
$ whoami
To check an account for sudo permissions
$ sudo whoami
regards,
T.Dhanasekar
who - show who is logged on
To print who command output without options
$ who
To print the heading of the columns displayed
$ who -H
To print the login names and total number of logged on users
$ who -q
To show only hostname and user associated with stdin
$ who -m
To add user's message status as +, - or ?
$ who -T
To view the time of last system boot
$ who -b
To check the current runlevel
$ who -r
To print dead processes
$ who -d
To see active processes spawned by init
$ who -p
To print last system clock change
$ who -t
To list users logged in
$ who -u
To print same as -b -d --login -p -r -t -T -u
$ who -a
regards,
T.Dhanasekar
which - locate a command
syntax
$ which -a [argument]
To locate a command
$ which -a touch
$ which -a free
$ which -a du
$ which -a df
regards,
T.Dhanasekar
whereis - is used to find the location of the binary, source, and manual
page files
syntax
$ whereis [OPTIONS] FILE_NAME...
To find the directories where the whereis command search
$ whereis -l
To get information about the commands
$ whereis du
$ whereis free
$ whereis bash
To get output for multiple commands
$ whereis du free bash
To search only for sources
$ whereis -s free
To search only for man files
$ whereis -m du
To search only for binaries
$ whereis -b cp
$ whereis -b free
regards,
T.Dhanasekar
whatis - display one-line manual page descriptions
syntax
$ Whatis [ command ]
$ whatis cp
$ whatis ls
$ whatis df
$ whatis du
$ whatis free
$ whatis cp ls df du free
To get help options
$ whatis --help
To get debugging information
$ whatis -d cp
$ whatis -d pwd
To get verbose details
$ whatis -v pwd
$ whatis -v free
To use regular expressions with this
$ whatis -r free
$ whatis -r ls
$ whatis -r pwd
To use wildcard with this
$ whatis -w free
regards,
T.Dhanasekar
wget - is a free utility for non-interactive download of files from the Web
To download a file with wget
$ wget http://path/to/url
To download file with different name
$ wget -O file.zip http://path/to/url.zip
To download multiple files with http and ftp
$ wget http://path/to/url ftp://path/to/url
To download multiple files from a file
$ cat downloads.txt
http://path/to/url1http://path/to/url2http://path/to/url3
$ wget -i downloads.txt
To resume uncompleted download
$ wget -c https://path/to/url_download
To download files in background
$ wget -b wget.log https://path/to/download_url
To Set File Download Speed Limits
$ wget -c --limit-rate=500k -b wget.log https://path/to/download_url
To download password protected files via http and ftp
$ wget --ftp-user=user1 --ftp-password=pa55code ftp://ftp_url
$ wget --http-user=user2 --http-password=pa55code http://http_url
regards,
T.Dhanasekar
