Merge pull request #99 from terminalforlife/master

More Comments & Code Tweaks & Additions

sheets/_cpp/func

@@ -26,4 +26,3 @@ int functionName(int &referenceName) {}
 
 // Pass by value (the caller and callee have two independent variables with the same value)
 int functionName(int valueName) {}
-

sheets/_cpp/pointers

@@ -1,8 +1,15 @@
-int *int_Ptr;     		// Declare a pointer variable called iPtr pointing to an int (an int pointer)
-                		// It contains an address. That address holds an int value.
-double *double_Ptr;  	// Declare a pointer of type double.
+// Declare a pointer variable called iPtr pointing to an int (an int pointer)
+// It contains an address. That address holds an int value.
+int *int_Ptr;
 
-int a = 5;				// Initializes a to the integer value 5 
-int *int_Ptr = &a		// Set int_Ptr which is an int pointer to the address of a
-std::cout << int_Ptr;	// Returns the address of a 
-std::cout << *int_Ptr;	// Returns 5 because it dereference the pointer to retrieve the value of a.
+// Declare a pointer of type double.
+double *double_Ptr;
+
+// Initializes a to the integer value 5
+int a = 5;
+// Set int_Ptr which is an int pointer to the address of `a`.
+int *int_Ptr = &a
+// Returns the address of `a`.
+std::cout << int_Ptr;
+// Returns 5 because it dereference the pointer to retrieve the value of `a`.
+std::cout << *int_Ptr;

sheets/_go/slices

@@ -1,14 +1,24 @@
-var a []int                              // declare a slice - similar to an array, but length is unspecified
-var a = []int {1, 2, 3, 4}               // declare and initialize a slice (backed by the array given implicitly)
-a := []int{1, 2, 3, 4}                   // shorthand
-chars := []string{0:"a", 2:"c", 1: "b"}  // ["a", "b", "c"]
+// declare a slice - similar to an array, but length is unspecified
+var a []int
+// declare and initialize a slice (backed by the array given implicitly)
+var a = []int {1, 2, 3, 4}
+// shorthand
+a := []int{1, 2, 3, 4}
+// ["a", "b", "c"]
+chars := []string{0:"a", 2:"c", 1: "b"}
 
-var b = a[lo:hi]	// creates a slice (view of the array) from index lo to hi-1
-var b = a[1:4]		// slice from index 1 to 3
-var b = a[:3]		// missing low index implies 0
-var b = a[3:]		// missing high index implies len(a)
-a =  append(a,17,3)	// append items to slice a
-c := append(a,b...)	// concatenate slices a and b
+// creates a slice (view of the array) from index lo to hi-1
+var b = a[lo:hi]
+// slice from index 1 to 3
+var b = a[1:4]
+// missing low index implies 0
+var b = a[:3]
+// missing high index implies len(a)
+var b = a[3:]
+// append items to slice a
+a =  append(a,17,3)
+// concatenate slices a and b
+c := append(a,b...)
 
 // create a slice with make
 a = make([]byte, 5, 5)    // first arg length, second capacity

sheets/_python/loops

@@ -32,17 +32,17 @@ else:
 # Basic 'for' loop:
 for i in range(6):
     print(i) #prints 0, 1, 2, 3, 4, 5
-
+#
 for i in range(2, 6):
     print(i) #prints 2, 3, 4, 5
-
+#
 for i in range(3, 10, 2):
     print(i) #prints 3, 5, 7, 9
 
 # Iterating through collections:
 for i in [0, 1, 1, 2, 3, 5]:
     print(i) #prints 0, 1, 1, 2, 3, 5
-
+#
 for i in 'qwerty':
     print(i) #prints q, w, e, r, t, y
 

sheets/awk

@@ -1,7 +1,7 @@
-# sum integers from a file or stdin, one integer per line:
+# sum integers from a file or STDIN, one integer per line:
 printf '1\n2\n3\n' | awk '{ sum += $1} END {print sum}'
 
-# using specific character as separator to sum integers from a file or stdin
+# using specific character as separator to sum integers from a file or STDIN
 printf '1:2:3' | awk -F ":" '{print $1+$2+$3}'
 
 # print a multiplication table
@@ -16,31 +16,36 @@ awk -v RS='' '/42B/' file
 # display only first column from multi-column text
 echo "first-column  second-column  third-column" | awk '{print $1}'
 
-# Use awk solo; without the need for something via STDIN.
+# Use AWK solo; without the need for something via STDIN.
 awk BEGIN'{printf("Example text.\n")}'
 
-# Accessing environment variables from within awk.
+# Accessing environment variables from within AWK.
 awk 'BEGIN{print ENVIRON["LS_COLORS"]}'
 
 # One method to count the number of lines; in this case, read from STDIN.
 free | awk '{i++} END{print i}'
 
-# Output a (unique) list of available sections under which to create a DEB package.
+# Output unique list of available sections under which to create a DEB package.
 awk '!A[$1]++{print($1)}' <<< "$(dpkg-query --show -f='${Section}\n')"
 
-# Using process substitution (`<()` is NOT command substitution), with AWK and its
-# associative array variables, we can print just column 2 for lines whose first
-# column is equal to what's between the double-quotes.
+# Using process substitution (`<()` is NOT command substitution), with AWK and
+# its associative array variables, we can print just column 2 for lines whose
+# first column is equal to what's between the double-quotes.
 awk '{NR!=1&&A[$1]=$2} END{print(A["Mem:"])}' <(free -h)
-# While below is an easier and simpler solution to the above, it's not at all the
-# same, and in other cases, the above is definitely preferable; more accurate.
+# While below is an easier and simpler solution to the above, it's not at all
+# the same, and in other cases, the above is definitely preferable.
 awk '/^Mem:/{print($2)}' <(free -h)
 
-# Output a unique-d list of uppercase-only, sigil-omitted variables used in [FILE].
+# Output list of unique uppercase-only, sigil-omitted variables used in [FILE].
 awk '{for(F=0; F<NF; F++){if($F~/^\$[A-Z_]+$/){A[$F]++}}} END{for(I in A){X=substr(I, 2, length(I)); printf("%s\n", X)}}' [FILE]
 
-# Output only lines from FILE between PATTERN_1 and PATTERN_2. Good for log files.
+# Output only lines from FILE between PATTERN_1 and PATTERN_2. Good for logs.
 awk '/PATTERN_1/,/PATTERN_2/{print}' [FILE]
 
 # Pretty-print a table of an overview of the non-system users on the system.
 awk -SPF ':' 'BEGIN {printf("%-17s %-4s %-4s %-s\n", "NAME", "UID", "GID", "SHELL")} $3>=1000 && $1!="nobody" {printf("%-17s %-d %-d %-s\n", $1, $3, $4, $7)}' /etc/passwd
+
+# Display the total amount of MiB of RAM available in the machine. This is also
+# a painful but useful workaround to get the units comma-separated, as would be
+# doable with Bash's own `printf` built-in.
+awk '/^MemTotal:/ {printf("%'"'"'dMiB\n", $2 / 1024)}'

sheets/cat

@@ -1,2 +1,16 @@
 # POSIX-ly correct way in which to cat(1); see cat(1posix).
 cat -u [FILE_1 [FILE_2] ...]
+
+# Output a file, expanding any escape sequences (default). Using this short
+# one-liner let's you view the boot log how it was show at boot-time.
+cat /var/log/boot.log
+
+# This is an ever-popular useless use of cat.
+cat /etc/passwd | grep '^root'
+# The sane way:
+grep '^root' /etc/passwd
+
+# If in bash(1), this is often (but not always) a useless use of cat(1).
+Buffer=`cat /etc/passwd`
+# The sane way:
+Buffer=`< /etc/passwd`

sheets/dd

@@ -1,26 +1,42 @@
 # Read from {/dev/urandom} 2*512 Bytes and put it into {/tmp/test.txt}
-# Note: At the first iteration, we read 512 Bytes.
-# Note: At the second iteration, we read 512 Bytes.
-dd if=/dev/urandom of=/tmp/test.txt count=512 bs=2
+# Note: both iterations each read 512 Bytes (the selected block size).
+dd if=/dev/urandom of=/tmp/test.txt count=2 bs=512
 
-# Watch the progress of 'dd'
-dd if=/dev/zero of=/dev/null bs=4KB &; export dd_pid=`pgrep '^dd'`; while [[ -d /proc/$dd_pid ]]; do kill -USR1 $dd_pid && sleep 1 && clear; done
+# Watch the progress of dd(1).
+dd if=/dev/zero of=/dev/null bs=4KB &
+export dd_pid=`pgrep '^dd'`
+while [[ -d /proc/$dd_pid ]]; do
+    kill -USR1 $dd_pid && sleep 1
+    clear
+done
 
-# Watch the progress of 'dd' with `pv` and `dialog` (apt-get install pv dialog)
-(pv -n /dev/zero | dd of=/dev/null bs=128M conv=notrunc,noerror) 2>&1 | dialog --gauge "Running dd command (cloning), please wait..." 10 70 0
+# Watch the progress of dd(1) with pv(1) and dialog(1), both of which can be
+# installed with the following command: apt-get install pv dialog
+(
+    pv -n /dev/zero | dd of=/dev/null bs=128M conv=notrunc,noerror
+) 2>&1 | dialog --gauge "Running dd command (cloning), please wait..." 10 70 0
 
-# Watch the progress of 'dd' with `pv` and `zenity` (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
+# Watch the progress of dd(1) with pv(1) and zenity(1), both of which can be
+# 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
 
-# Watch the progress of 'dd' with the built-in `progress` functionality (introduced in coreutils v8.24)
+# Watch the progress of dd(1) with the built-in `progress` functionality, -
+# introduced in coreutils v8.24.
 dd if=/dev/zero of=/dev/null bs=128M status=progress
 
 # DD with "graphical" return
 dcfldd if=/dev/zero of=/dev/null bs=500K
 
-# This will output the sound from your microphone port to the ssh target computer's speaker port. The sound quality is very bad, so you will hear a lot of hissing.
+# This will output the sound from your microphone port to the ssh target
+# computer's speaker port. The sound quality is very bad, so you will hear a
+# lot of hissing.
 dd if=/dev/dsp | ssh -c arcfour -C username@host dd of=/dev/dsp
 
 # Show current progress without interruption (USR1)
 dd if=/dev/zero of=/dev/null & pid=$!
 kill -USR1 $pid
+
+# Create a 1GiB file with nothing but zeros, ready to mkswap(8) it.
+dd if=/dev/zero of=/swapfile count=1048576 bs=1024 status=progress

sheets/df

@@ -1,14 +1,17 @@
-# Printout disk free space in a human readable format
+# Print free disk space in a [h]uman-readable format.
 df -h
 
-# Disk free space for ext2 file systems
+# Free disk space for [t]ype EXT2 file systems.
 df -t ext2
 
-# Disk free space for file systems except ext2
+# Free disk space for filesystems, e[x]cluding EXT2.
 df -x ext2
 
-# Show inode usage
+# Show [i]node usage.
 df -i
 
-# Show information about a distinct file system /path
-df /path
+# Show information about a distinct filesystem path.
+df [PATH]
+
+# List [a]ll filesystems, + unreadable, duplicates, pseudo, and inaccessible.
+df -a

sheets/exec

@@ -1,17 +1,17 @@
 # exec
 #
 # Shell builtin command
-# It can start a new process to replace the shell, without a new process creation.
-# It can make redirections take effect in the current shell
+# It can start a new process to replace the shell, without a new process
+# creation. It can make redirections take effect in the current shell
 
-# Redirect the output of an entire shell script within the script itself
-# Only stdout:
+# Redirect all STDOUT from within a script to the given file.
 exec > foo.log
 
-# Redirect the output of an entire shell script within the script itself
-# Stdout and stderr:
+# Redirect all of both STDOUT & STDERR from within a script to the given file.
 exec > foo.log 2>&1
+# Or, if on bash(1), this syntax is also viable:
+exec &> foo.log
 
-# Copy output to a log file
+# Copy output to a log file, allowing the outputs to still work as usual.
 exec >  >(tee -ia foo.log)
 exec 2> >(tee -ia foo.log >&2)

sheets/fdisk

@@ -1,10 +1,5 @@
-# list partitions
-fdisk -l /dev/sda
-
-# delete a partition
-fdisk /dev/sda
-Command (m for help): d
-Partition number (1-9): XXX
+# List partitions on BLKDEV, such as `/dev/sda`.
+fdisk -l [BLKDEV]
 
 # Usage:
 #   fdisk [options] <disk>    change partition table

sheets/i3

@@ -101,16 +101,18 @@ bindsym $mod+4 workspace $ws4
 bindsym $mod+Shift+R exec custom-script-in-path.sh --flag1 --flag2
 bindcode 172 exec playerctl play-pause
 
-# Always execute code when i3 starts:
+# Execute code when i3 starts, but only once per session:
 exec --no-startup-id ~/.config/polybar/launch.sh
+# Always execute code when i3 starts, even if it's simply restarted:
+exec_always --no-startup-id ~/.config/polybar/launch.sh
 
 # One can make special modes (much like resize mode)
 set $gamingMode "gaming_mode"
 bindsym $mod+g mode $gamingMode
 mode $gamingMode {
-   # Insert declarations for this mode
-   # Useful when normal keybindings fight with keybindings of your games
-   # Don't forget to add option to return from this mode!
+    # Insert declarations for this mode. Useful when normal keybindings fight
+    # with keybindings of your games. Don't forget to add option to return from
+    # this mode!
     bindsym $mod+Escape mode default
 }
 

sheets/lshw

@@ -1,33 +1,33 @@
 # lshw
 # Get hardware information on Linux
 
-# Generate full information report about all detected hardware
+# Generate full information report about all detected hardware.
 lshw
 
-# Display hardware information in short
+# Display brief hardware information.
 lshw -short
 
-# Display only memory information
+# Display only memory information.
 lshw -short -class memory
 
-# Display processor information
+# Display processor information.
 lshw -class processor
 
-# Display the disk drives with the disk class
+# Display the disk drives with the disk class.
 lshw -short -class disk
 
 # Display information about the partitions and controllers also,
-# specify the storage and volume class along with the disk class
+# specify the storage and volume class along with the disk class.
 lshw -short -class disk -class storage -class volume
 
-# Network adapter information
+# Network adapter information.
 lshw -class network
 
-# Display the address details of pci, usb, scsi and ide devices
+# Display the address details of PCI, USB, SCSI and IDE devices.
 lshw -businfo
 
-# Generate report in html format
+# Generate report in HTML format.
 lshw -html > hardware.html
 
-# Generate report in xml format
+# Generate report in XML format.
 lshw -html > hardware.html

sheets/printf

@@ -10,3 +10,9 @@ printf '%s\n' "$USER"
 # one million, in a human-readable kind of way, by appropriately
 # comma-separating the units.
 printf "%'d\n" {1..1000000}
+
+# Zero-pad a number in order to maintain a width of 3 characters.
+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.
+printf '%3d\n' 12

sheets/proc

@@ -12,3 +12,6 @@ cat /proc/<pid>/status
 
 # See every file the process has open
 ls -l /proc/<pid>/fd
+
+# Display some useful memory statistics, often used by programs like htop(1).
+cat /proc/meminfo

sheets/python

@@ -10,10 +10,10 @@ python -m SimpleHTTPServer
 # Python 3
 python -m http.server 8000
 
-# SMTP-Server for debugging, messages will be discarded, and printed on stdout.
+# SMTP-Server for debugging, messages will be discarded, and printed on STDOUT.
 python -m smtpd -n -c DebuggingServer localhost:1025
 
-# Pretty print a json
+# Pretty print a JSON
 python -mjson.tool
 
 # Zen of Python

sheets/sgdisk

@@ -22,7 +22,7 @@ sgdisk -l=sgdisk-sda.bak
 # Clone your current device's partition layout '/dev/sda' to another drive '/dev/sdc'
 sgdisk -R=/dev/sdc /dev/sda
 
-# If both drives will be in the same computer, you need to randomize the GUID's after cloning
+# If both drives will be in the same computer, you need to randomize the GUIDs after cloning
 sgdisk -G /dev/sdc
 
 

sheets/siteciphers

@@ -1,7 +1,7 @@
 # siteciphers (Bash-Snippets)
-# Checks the available ciphers for the SSL of an https site.
+# Checks the available ciphers for the SSL of an HTTPS site.
 
-# Determine the available SSL ciphers for an https website
+# Determine the available SSL ciphers for an HTTPS website
 siteciphers github.com
 
 # Determine the ciphers setting the delay between requests (default is 1 sec)

sheets/source

@@ -1,6 +1,6 @@
-# This is a shell builtin available in bash, but not in the Bourne Shell (`sh`).
-# The contents of FILE (assuming shell script) will be sourced into the current
-# session, allowing external use of things like its functions and variables.
+# This is a shell built-in available in Bash, but not in the Bourne Shell
+# (`sh`). The contents of FILE (assuming shell script) will be sourced into the
+# current session, allowing external use of its functions, variables, etc.
 source FILE
 # The above can be written in short-hand, for the same effect:
 . FILE

sheets/svgo

@@ -1,28 +1,30 @@
 # svgo
 #
-# SVG Optimizer: a Nodejs-based tool for optimizing Scalable Vector Graphics files.
-# It applies a series of transformation rules (plugins), which can be toggled individually.
+# SVG Optimizer: a Node.js-based tool for optimizing Scalable Vector Graphics
+# files. It applies a series of transformation rules (plugins), which can be
+# toggled individually.
 
-# Optimize a file using the default plugins (overwrites the original file):
+# Optimize a file using the default plugins, overwriting the original file.
 svgo test.svg
 
-# Optimize a file and save the result to another file:
+# Optimize a file and save the result to another file.
 svgo test.svg test.min.svg
 
-# Optimize all SVG files within a folder (overwrites the original files):
-svgo -f path/to/folder/with/svg/files
+# Optimize all SVG files within a directory, overwriting the original files.
+svgo -f path/to/directory/with/svg/files
 
-# Optimize all SVG files within a folder and save the resulting files to another folder:
-svgo -f path/to/input/folder -o path/to/output/folder
+# Optimize all SVG files within a directory and save the resulting files to
+# another directory.
+svgo -f path/to/input/dir -o path/to/output/dir
 
-# Optimize SVG content passed from another command, and save the result to a file:
+# Optimize SVG content passed from another command, then save result to a file.
 cat test.svg | svgo -i - -o test.min.svg
 
-# Optimize a file and print out the result:
+# Optimize a file and print out the result.
 svgo test.svg -o -
 
-# Optimize a file making sure a given plugin is enabled:
+# Optimize a file making sure a given plugin is enabled.
 svgo --enable=plugin_name
 
-# Show available plugins:
+# Show available plugins.
 svgo --show-plugins

sheets/weather

@@ -1,10 +1,10 @@
 # weather (Bash-Snippets)
-# Provides a 3 day forecast on your current location or a specified location
+# Provides a 3-day forecast on your current location or a specified location
 
-# Get a 3 day forecast for your current location as determined by your ip address
+# Get 3-day forecast for your current location as determined by your IP address
 weather
 
-# Get a 3 day forecast for any location
+# Get 3-day forecast for any location
 weather Tokyo
 
 # Get the current moon phase