who command
The who command prints information
about all users who are currently logged in.
The basic who command with no
command-line arguments shows the names of users that are currently logged in,
and depending on which Unix/Linux system you are using, may also show the
terminal they're logged in on, and the time they logged in.
Syntax
The basic syntax is as follows:
Who
Displays the username, line, and
time of all currently logged-in sessions. For example:
who am i
Displays the same information, but
only for the terminal session where the command was issued, for example:
alan pts/3 2013-12-25 08:52 (:0.0)
who [options] [File]
cal examples
Options
-a, --all
The -a argument
of the who command lists all available output for each user on your system.
-b, --boot
Display the
time of the last system boot.
-d, --dead
Display
dead processes.
-H, --heading
Print a
line of column headings.
--ips
Print IP addresses
instead of hostnames. With --lookup, canonicalizes based on
stored IP, if available, rather than stored hostname.
-l, --login
Print
system login processes.
--lookup
Attempt to
canonicalize hostnames via DNS.
-m
Only print
information about the user and host associated with standard input (the terminal where
the command was issued). This method adheres to the POSIX standard.
-p, --process
Print
active processes spawned by init.
-q, --count
Displays
all login names, and a count of all logged-on users.
-r, --runlevel
Print the
current runlevel.
-s, --short
Print only
name, line, and time fields, which is the default.
-t, --time
Print the
last time the system clock was changed, if the
information is available.
-T, -w, --mesg
Add
a character which indicates the state of the terminal line: "+"
if the terminal is writable, "-" if it is not, or "?"
if a bad line is encountered.
-u, --users
Print the
idle time for each user, and the process ID.
--message
Same
as -T.
--writable
Same
as -T.
--help
Display a
help message, and exit.
--version
Display
version information, and exit.
-a, --all
The -a argument
of the who command lists all available output for each user on your system.
-b, --boot
Display the
time of the last system boot.
-d, --dead
Display
dead processes.
-H, --heading
Print a
line of column headings.
--ips
Print IP addresses
instead of hostnames. With --lookup, canonicalizes based on
stored IP, if available, rather than stored hostname.
-l, --login
Print
system login processes.
--lookup
Attempt to
canonicalize hostnames via DNS.
-m
Only print
information about the user and host associated with standard input (the terminal where
the command was issued). This method adheres to the POSIX standard.
-p, --process
Print
active processes spawned by init.
-q, --count
Displays
all login names, and a count of all logged-on users.
-r, --runlevel
Print the
current runlevel.
-s, --short
Print only
name, line, and time fields, which is the default.
-t, --time
Print the
last time the system clock was changed, if the
information is available.
-T, -w, --mesg
Add
a character which indicates the state of the terminal line: "+"
if the terminal is writable, "-" if it is not, or "?"
if a bad line is encountered.
-u, --users
Print the
idle time for each user, and the process ID.
--message
Same
as -T.
--writable
Same
as -T.
--help
Display a
help message, and exit.
--version
Display
version information, and exit.
who | grep 'userNameHere'
This command is use to find the
particular user.
Linux Command - cal
Cal displays a simple calendar.
cal syntax
cal [options] [[[day] month] year]
Options
-1
|
Display a single month, which is the default
setting.
|
-3
|
Display three months: last month, this month, and
next month.
|
-s
|
Display the calendar using Sunday as the first day
of the week.
|
-m
|
Display Monday as the first day of the week.
|
-j
|
Display dates of the Julian calendar.
|
-y
|
Display a calendar for the entire current year.
|
cal examples
If arguments are not specified, the current
month is displayed
cal
Displays the calendar for this
month.
cal 12 2000
Displays the calendar for December
of the year 2000.
To display complete year calendar.
cal –y
banner command
'banner' is a command which prints
a high resolution text banner on the system console or if you have a printer
connected to your machine, you can redirect the output to the printer.
For example,
$ banner -w 50 Ravi
The above command will print the
name on the console with a width of 50 characters. If the -w option is omitted,
it prints the name in the default width of 102 characters. The character used
to print the name is '#'.
You can also redirect the output
to a printer as follows:
$ banner -w 60 Ravi > /dev/lp0
The touch Command
The touch command is the easiest
way to create new, empty files. It is also used to change the timestamps (i.e.,
dates and times of the most recent access and modification) on existing files
and directories.
touch's syntax is
touch [option] file_name(s)
When used without any options,
touch creates new files for any file names that are provided as arguments
(i.e., input data) if files with such names do not already exist. Touch can
create any number of files simultaneously.
Thus, for example, the following
command would create three new, empty files named file1, file2 and file3:
touch file1 file2 file3
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