displays info about the users currently logged on and their processes.
If user is specified, ~ shows info about this user only.
w [options] [user]
The following entries are displayed for each user: login name, tty, remote host, login time, idle time, JCPU, PCPU, and the cmd line of their current process.
JCPU is the time used by all processes attached to the tty. It does not include past background jobs, but does include currently running background jobs.
PCPU is the time used by the current process, named in WHAT field.
Options
--help -V
--version
-f |
toggle FROM field (remote host); |
-h |
don't show the header; |
-s |
use short format (omit login time, JCPU, PCPU); |
-u |
ignore username while figuring out curr process and cpu time; |
counts bytes, words, lines in text files.
wc [options] [files]
If file spec is missing or '-' is used, ~ gets
data from stdin.
ls -l | wc -l
show the number of entries in the current dir (except . / .. and hidden);
wc -c notes.html
wc -m notes.html
count the number of bytes (1) and chars (2) in the specified file; for UTF8 encoding the first number can be greater;
wc -w readme.txt
count words in the specified text file;
Options
--help --version
-c, --bytes
count bytes;
-m, --chars
count characters;
-l, --lines
count lines;
-L, --max-line-length
show the length of the longest line;
-w, --words
count words;
is non-interactive network downloader.
wget [options] ... [URL] ...
It supports HTTP, HTTPS, FTP and retrieval through HTTP proxies. It has many options, not all of them are described here. Use quotes to specify URL containing '&'.
wget -m http://www.abcd.com
mirror the web-site www.abcd.com;
wget -i updates.lst
download files specified in updates.lst (text file, each line is URL, like http://download.fedora...);
wget -H -r --level=1 -k -p http://www.bum.com
download all pages on the specified site plus 1 (one) level into any other site it links to, convert links in downloaded pages for local access, get all components (images, etc);
wget -c --output-document=movie4.avi http://...
resume download of a large file that was not completely transferred in the previous session;
Some options
-h --help
-V --version
-v --verbose
-a logfile,
--append-output=logfile
append messages to the specified log file (create new, if it doesn't exist);
-b, --background
go to the background immediately after startup;
without -o output is redirected to wget-log;
-c, --continue
continue getting a partially-downloaded file;
should be used to resume download started by the previous instance of
~; current instance in case of a connection break resumes
download from the correct point by default;
-H, --span-hosts
enable spanning across hosts when performing recursive retrieving;
-i file,
--input-file=file
read URLs from file;
-k, --convert-links
convert links in the downloaded documents to make them suitable for local viewing;
-l n,
--level=n
set max depth of recursion (default is 5);
-L, --relative
follow relative links only;
-m, --mirror
turn on options suitable for mirroring (recursion,
time-stamping, etc; it is currently equivalent to -r -N -l inf
--no-remove-listing;
-N, --timestamping
turn on time-stamping;
-o logfile,
--output-file=logfile
log all messages to the specified file (default is stderr), overwrite old;
-O file,
--output-document=file
don't save each document separately, but concatenate and write to file;
-p, --page-requisites
download all files required to properly display a HTML page (images, sounds, stylesheets);
-q, --quiet
turn off ~ output;
-r, --recursive
turn on recursive retrieving;
-t n,
--tries=n
set the number of retries to n; 0
means infinite (also inf), default is 20 except
fatal errors (404, etc);
-w n,
--wait=n
wait n sec between the retrievals;
--no-proxy
don't use proxy, even if the appropriate *_proxy env variable is defined;
--user=user
--password=pass
set username / password for both HTTP and FTP file retrieval; there are also separate:
--ftp-user |
--ftp-password |
|
--http-password |
|
--proxy-password |
Each man page contains a short one-line page description, and
whatis can find and display this description using a set
of index databases updated by mandb program (usually auto).
whatis [options] name ...
With the appropriate options (see below) name can include wildcards and regular expressions. However, sometimes it may be necessary to quote names or escape (\) special chars to stop shell from interpreting them.
Some options
-? --help
--usage
-V --version
-v --verbose
-r, --regex
interpret each name as a regular expression,
and try to match any part of a page name; this option slows ~
down a little bit;
-w, --wildcard
interpret each name as a pattern containing
shell-style wildcards; for a match to be made, an expanded name must match
the entire page name; this option slows ~ down a little bit;
-l, --long
do not trim output to the terminal width (normally, output is truncated to the terminal width to avoid ugly display of the poorly-written NAME sections);
locates source, binary and manuals sections for the specified files.
whereis [-bmsu] [-BMS dir ... -f] filename ...
The filename is first stripped of leading pathname components and any single trailing extension, then searched in standard Linux places.
whereis rar
search for rar binary, source, and manual
sections everywhere (i.e., in all standard Linux places);
whereis -b -B /usr/bin -f wget
search for wget executable file in
/usr/bin only;
whereis -B /usr/bin -f wget
search for wget executable in
/usr/bin, also search for source and manual sections in
standard places;
Options
-b |
search only for binaries; |
-m |
search only for manual sections; |
-s |
search only for sources; |
-u |
search for unusual entries (a file is unusual if it does not have one entry of each requested type); |
-B |
change or otherwise limit places to be searched for binaries; |
-M |
change or otherwise limit places to be searched for manual sections; |
-S |
change or otherwise limit places to be searched for sources; |
-f |
terminate the last dir list and signal the start of file
names (must be used with -B, -M, -S); |
locates the specified command and shows the pathname of its executable file.
which [-a] command ...
~ returns the pathnames of the files (or links) which would
be executed in the current env, had the command (or commands) been
given as a command (or commands) in a strictly POSIX-conformant shell. It does
this by searching the paths in the PATH env var for executable
files matching the names of the commands given to ~ as args.
Note that ~ does not follow symlinks.
which gcc
shows the full path of GNU C compiler that will be started by default;
which -a sqlplus
shows the full paths of all versions of Oracle
SQL*Plus, if any; even if ~ shows nothing, it does not
mean that subj is totally missing, it only means subj cannot be found using
PATH;
Options
-a |
display all matching pathnames of each matching command; |
| 0 | all specified cmds are found and executable; |
| 1 | one or more specified cmds is non-existent or not executable; |
| 2 | an invalid option was specified; |
shows who is logged on.
who [options]
[file | arg1 | arg2]
By default /var/run/utmp is used to get info.
who -b
show the boot time (when the system was started);
who am i
show who is logged on this terminal (note, that this is
not equivalent to whoami);
Options
--help --version
-a, --all
same as -b -d --login -p -r -t -T -u;
-b, --boot
time of last system boot;
-d, --dead
show dead processes;
-H, --heading
show column headers;
-i, --idle
add idle time as hours:minutes;
-l, --login
show system login processes;
-m |
show only hostname and user associated with stdin; |
-p, --process
print active processes spawned by init;
-q, --count
show login names and num of users logged on;
-r, --runlevel
show current runlevel;
-s, --short
show only name, line and time (default);
-t, --time
show last system clock change;
-T,
--mesg, -w,
--message, --writable
add user's message status as +, -, ?;
-u, --users
list users logged in;