Merge pull request #100 from terminalforlife/master

Wording, Formatting, & Entries

sheets/colrm

@@ -0,0 +1,7 @@
+# colrm
+# Remove columns from a file or STDIN
+
+# Remove the first, second, third, and fourth column.
+colrm 1 4 [FILE]
+# Same approach as the above, but via STDIN.
+printf 'Some of this is omitted.' | colrm 1 4

sheets/dd

@@ -1,5 +1,8 @@
-# Read from {/dev/urandom} 2*512 Bytes and put it into {/tmp/test.txt}
+# dd
-# Note: both iterations each read 512 Bytes (the selected block size).
+# Convert and copy a file (AKA: Destroyer of Disks)
+
+# Read from `/dev/urandom`, 2*512 Bytes, and put it into `/tmp/test.txt`.
+# Note: each iteration reads 512 bytes (the selected block size).
 dd if=/dev/urandom of=/tmp/test.txt count=2 bs=512
 
 # Watch the progress of dd(1).
@@ -20,10 +23,10 @@ done
 # installed with the following command: apt-get install pv zenity
 (
     pv -n /dev/zero | dd of=/dev/null bs=128M conv=notrunc,noerror
-) 2>&1 | zenity --title 'Running dd command (cloning), please wait...' --progress
+) 2>&1 | zenity --title 'Cloning with dd(1) -- please wait...' --progress
 
 # Watch the progress of dd(1) with the built-in `progress` functionality, -
-# introduced in coreutils v8.24.
+# introduced in CoreUtils v8.24.
 dd if=/dev/zero of=/dev/null bs=128M status=progress
 
 # DD with "graphical" return

sheets/df

@@ -1,3 +1,6 @@
+# df
+# Report file system disk space usage
+
 # Print free disk space in a [h]uman-readable format.
 df -h
 

sheets/printf

@@ -1,3 +1,10 @@
+# printf
+# Format and print data
+
+# This command is typically available as a built-in to many shells, such as the
+# Bourne shell and the Bourne Again Shell. However, there also exists a GNU
+# alternative, sometimes found over at `/usr/bin/printf`.
+
 # Assign the current date (timestamp style) as a shell variable, using the Bash
 # builtin, and make it a suitable filename for a Gzip-compressed Tar archive.
 printf -v FileName 'Backup_%(%F_%X)T.tgz' -1
@@ -10,8 +17,11 @@ printf '%s\n' "$USER"
 # one million, in a human-readable kind of way, by appropriately
 # comma-separating the units.
 printf "%'d\n" {1..1000000}
+# Getting these results by using the comma is actually also viable in AWK, but
+# you'll likely have to jump through a quotation hoop to get access to it.
 
-# Zero-pad a number in order to maintain a width of 3 characters.
+# Zero-pad a number in order to maintain a width of 3 characters. It's also
+# possible to instead provide a `0` in-place of the hash (`#`).
 printf '%#.3d\n' 12
 # As above, but instead, space-pad the number. Prefix the `3` with a hyphen
 # (`-`) to left-align the number, causing the padding to occur on the right.

sheets/source

@@ -1,6 +1,15 @@
-# This is a shell built-in available in Bash, but not in the Bourne Shell
+# source
-# (`sh`). The contents of FILE (assuming shell script) will be sourced into the
+# Execute commands from a file in the current shell
-# current session, allowing external use of its functions, variables, etc.
+
+# This is a shell built-in, available within most if not all shells. However, -
+# it may only be available as `.` in some older shells, such as Bourne shell.
+# Its first argument is a file, with all proceeding arguments being parameters
+# to the aforementioned file.
+
+# Run shell code residing within FILE as though you'd entered it in yourself.
 source FILE
-# The above can be written in short-hand, for the same effect:
+# The above can be written in short-hand, for the same effect, shell allowing.
 . FILE
+
+#  Source FILE with the given arguments to said file.
+source FILE Argument_1 Argument_2 Argument_3 ...

sheets/ss

@@ -1,5 +1,6 @@
-# Utility to investigate sockets
+# ss
-#
+# Another utility to investigate sockets
+
 # Options:
 #   -4/-6   list ipv4/ipv6 sockets
 #   -n      numeric addresses instead of hostnames
@@ -7,19 +8,23 @@
 #   -u/-t/-x list udp/tcp/unix sockets
 #   -p      Show process(es) that using socket
 
-# show all listening tcp sockets including the corresponding process
+# Show all listening TCP ports, including the corresponding process.
 ss -tlp
 
-# show all sockets connecting to 192.168.2.1 on port 80
+# Show a summary of all ports connecting to 192.168.2.1 via port 80.
 ss -t dst 192.168.2.1:80
 
-# show all ssh related connection
+# Show all SSH-related connection.
-# documentation on the filter syntax: sudo apt-get install iproute2-doc
+#
+# Documentation on the filter syntax can be installed via the following command
+# if on a Debian- or Ubuntu-based distribution of Linux:
+#
+#     sudo apt-get install iproute2-doc
+#
 ss -t state established '( dport = :ssh or sport = :ssh )'
 
-# Display timer information
+# Display timer information.
-ss -tn -o
+ss -tno
 
-# Filtering connections by tcp state
+# Filter connections by TCP state.
 ss -t4 state established
-

sheets/ssh

@@ -1,5 +1,5 @@
 # ssh
-# access a remote host via SSH
+# OpenSSH SSH client (remote login program)
 
 # SSH in via PEM file, which normally needs 0600 permissions.
 ssh -i /path/to/file.pem user@example.com
@@ -50,8 +50,10 @@ ssh -o PubkeyAuthentication=no username@hostname.com
 # Install SSHFS from: https://github.com/libfuse/sshfs
 sshfs name@server:/path/to/folder /path/to/mount/point
 
-# EMACS can read files through SSH.
+# EMACS can read files through SSH. Below, is a link to related documentation.
-# Doc: http://www.gnu.org/software/emacs/manual/html_node/emacs/Remote-Files.html
+#
+#   http://www.gnu.org/software/emacs/manual/html_node/emacs/Remote-Files.html
+#
 emacs /ssh:name@server:/path/to/file
 
 # Get help for SSH escape sequences. Useful for terminating unresponsive

sheets/stat

@@ -1,3 +1,6 @@
+# stat
+# Display file or file system status
+
 # display numerical values for file permissions
 stat -c '%a %n' *
 

sheets/sudo

@@ -1,33 +1,64 @@
 # sudo
-# Execute a command as another user.
+# Execute a command as another user
 
-# List of an unreadable directory:
+# List contents of directory to which the user otherwise wouldn't have access.
 sudo ls /usr/local/scrt
 
-# To edit a file as user www:
+# Edit the given file as the `www` user. This is a great example of why sudo(8)
+# is or was often, and more accurately, referred to as "substitute user do".
 sudo -u www vi /var/www/index.html
 
-# To shutdown the machine:
+# Shut down (halt) the machine when 10 minutes have passed. The quoted text is
+# messaged to the terminal of all applicable users, known as a 'wall message'.
 sudo shutdown -h +10 "Cya soon!"
+# Note, that the above is the old method. On machines with SystemD, the below
+# command can instead be used.
+sudo systemctl reboot
 
-# To repeat the last command as sudo:
+# In Bash, `!!` (bang, bang) is an event designator, as described in bash(1), -
+# and is used to refer to the previous command, synonymous for `!-1`.
+#
+# In this case, the user is able to prefix the entirety of the previous command
+# with `sudo`, being most useful when forgetting that `root` access is needed.
 sudo !!
 
-# Save a file you edited in vim
+# For use in the vim(1) modal text editor, this command allows the user to save
+# the currently opened file as the `root` user, despite having not previously
+# opened it with such privileges.
 :w !sudo tee > /dev/null %
 
-# Make sudo forget password instantly
+# Reset the current user's sudo(8) timestamp, resulting in the user having to
+# once again enter his or her password when next using sudo(8). Use of this
+# flag does not actually require `root` privileges.
 sudo -K
 
-# List your sudo rights
+# List the current user's sudo(8) privileges.
 sudo -l
 
-# Add a line to a file using sudo
+# Add a line to a file using sudo(8). This is especially useful when making
+# changes to a kernel parameter file, like the `/proc/sys/vm/swappiness` file.
 echo "foo bar" | sudo tee -a /path/to/some/file
 
-# run root shell
+# Begin a shell session as the system's `root` user.
 sudo -i
 
-# to disable password for sudo for user superuser add
+# To disable password for sudo(8) for the `superuser` user, add the below line
-# superuser ALL=(ALL) NOPASSWD:ALL
+# to the `/etc/sudoers` file, preferably by using the visudo(8) executable.
-# in /etc/sudoers
+#
+#     superuser ALL=(ALL) NOPASSWD: ALL
+#
+# This would result in the aforementioned user not needing to enter in a
+# password when using `sudo`, otherwise he or she would be required to do so.
+#
+# Likewise, the below can be entered if this is wished for an entire group, -
+# which in this case would be the `special` group.
+#
+#     %special ALL=(ALL) NOPASSWD: ALL
+#
+# Do note that neither of these configurations are at all recommended and can
+# pose a massive security risk.
+
+# Run `CMD` as the `root` user, but maintain the current user's environment. In
+# systems like Ubuntu, this is assumed, but systems like Debian would require
+# that the user make use of this flag when wanting to keep their environment.
+sudo -E [CMD]

sheets/wget

@@ -1,6 +1,12 @@
-# Quietly download a file, continuing where it left of, if the connection fails.
+# wget
-# Note that the file will be downloaded to the current working directory.
+# The non-interactive network downloader
+
+# Quietly download a file, continuing where it left of, if the connection
+# fails. The file will be downloaded to the current working directory.
 wget -qc [URL]
 
 # Specify a location to download the given file.
 wget -qcO [PATH] [URL]
+
+# Download URL using the user agent string provided to the `-U` flag.
+wget -U 'Mozilla/5.0' [URL]

sheets/xset

@@ -1,5 +1,5 @@
 # xset
-# user preference utility for X
+# User preference utility for X
 
 # Disable screen saver blanking
 xset s off