Minor fixes

Author: ellysh

manuscript/BashScripting/arithmetic-expression.md

@@ -263,7 +263,7 @@ Represent the following two-byte integers in the two's complement and add them:
 
 You have learned how a computer represents numbers in memory. Would you need this knowledge in practice?
 
-Modern programming languages take care of converting numbers to the correct format. For example, you declare a signed integer variable in decimal notation. You do not need to worry about how the computer stores it in memory. If the variable becomes negative, the computer applies the two's complement representation automatically.
+Modern programming languages take care of converting numbers to the correct format. For example, you declare a signed integer variable in decimal notation. You do not need to worry about how the computer stores it in memory. It stores all numbers in two's complement representation automatically.
 
 There are cases when you want to treat a variable as a set of bits. You declare it as a positive integer in this case. You should operate it in hexadecimal. Please do not convert this variable to decimal. This way, you avoid the problems of converting numbers.
 
@@ -817,19 +817,22 @@ The bitwise AND operate the numbers instead of Boolean expressions. These are st
 
 3. Take the bits of the numbers in the same position and apply the logical AND for them.
 
-Here is an example. You want to calculate the bitwise AND for numbers 5 and 3. First, you should represent them in the two's complement like this:
+Here is an example. You want to calculate the bitwise AND for numbers 5 and 3. First, you should represent their absolute values in binary like this:
 {line-numbers: false}
 ```
 5 = 101
 3 = 11
 ```
 
+
 The number 3 has fewer bits than 5. Therefore, you have to add an extra zero on its left side. This way, you get the following representation of the number 3:
 {line-numbers: false}
 ```
 3 = 011
 ```
 
+You should convert a number in the two's complement if it is negative.
+
 Now you should apply the logical AND for each pair of bits of the numbers. You can write the numbers in columns for convenience:
 {line-numbers: false}
 ```
@@ -855,7 +858,7 @@ echo $((5 & 3))
 
 The bitwise OR operation works similarly as bitwise AND. The only difference is it applies logical OR instead of AND for each pair of bits.
 
-Here is an example. Suppose that you need to calculate the bitwise OR for the numbers 10 and 6. First, you should write them in the two's complement representation this way:
+Here is an example. Suppose that you need to calculate the bitwise OR for the numbers 10 and 6. First, you should write them in binary this way:
 {line-numbers: false}
 ```
 10 = 1010
@@ -893,7 +896,7 @@ echo $((10 | 6))
 
 The bitwise exclusive OR (XOR) operation is similar to the bitwise OR. You should replace the logical OR with the **exclusive OR** when handling the bits of the numbers there. The exclusive OR returns "false" only when both operands have the same values. Otherwise, it returns "true".
 
-Let's calculate the exclusive OR for the numbers 12 and 5. First, represent them in the two's complement:
+Let's calculate the exclusive OR for the numbers 12 and 5. First, represent them in binary:
 {line-numbers: false}
 ```
 12 = 1100
@@ -951,15 +954,15 @@ Any bit shift operation takes two operands. The first one is some integer, which
 
 Here is an algorithm for doing the logical bit shift:
 
-1. Represent the integer in the two's complement.
+1. Represent the integer in binary.
 
 2. Discard the required amount of bits on the RHS for the right shift and the LHS for the left shift.
 
 3. Append zeroes on the opposite side of the number. This is LHS for the right shift and RHS for the left shift. The amount of zeroes matches the number of shifted bits.
 
 Here is an example. You need to do a logical right shift of the unsigned integer 58 by three bits. The integer occupies one byte of memory.
 
-First, you represent the number in the two's complement:
+First, you represent the number in binary:
 {line-numbers: false}
 ```
 58 = 0011 1010

manuscript/BashScripting/conditional-statement.md

@@ -506,7 +506,7 @@ You can choose the mode by passing a command-line option to the script. Table 3-
 | `-c` | Archiving with compression |
 | `-x` | Unarchiving |
 
-I> Always follow the [POSIX agreement](https://www.gnu.org/software/libc/manual/html_node/Argument-Syntax.html) and its [GNU extension](https://www.gnu.org/prep/standards/html_node/Command_002dLine-Interfaces.html) when choosing options and parameters format for your scripts. Then users can learn them faster.
+I> Always follow the [POSIX convention](https://www.gnu.org/software/libc/manual/html_node/Argument-Syntax.html) and its [GNU extension](https://www.gnu.org/prep/standards/html_node/Command_002dLine-Interfaces.html) when choosing options and parameters format for your scripts. Then users can learn them faster.
 
 You can check the script option using the `if` statement. Listing 3-12 shows how this solution looks like.
 

manuscript/BashScripting/loop-operators.md

@@ -101,7 +101,7 @@ When the script receives the response from the server, it should print a message
 
 You can call the [`ping`](https://en.wikipedia.org/wiki/Ping_(networking_utility)) utility to send a request to the server. The utility uses the [ICMP](https://en.wikipedia.org/wiki/Internet_Control_Message_Protocol) **protocol**.
 
-The protocol is an agreement for the format of messages between the computers of the network. The ICMP protocol describes the messages to serve the network. For example, you need them to check if some computer is available.
+The protocol is an agreement for the format of messages between the computers of the network. The ICMP protocol describes the error messages and packets with operational information. For example, you need them to check if some computer is available.
 
 When calling the `ping` utility, you should specify an [IP address](https://en.wikipedia.org/wiki/IP_address) or [URL](https://en.wikipedia.org/wiki/URL) of the target **host**. A host is a computer or device connected to the network.
 

manuscript/BashShell/file-system.md

@@ -751,7 +751,9 @@ Here is an example of using the `-r` option:
 grep -r "free software" .
 ```
 
-This command finds the "free software" phrase in the files of the current directory. It processes the hidden objects too. If you work on Linux or macOS, prefer the `-R` option instead of `-r`. It forces `grep` to follow [**symbol links**](https://en.wikipedia.org/wiki/Symbolic_link) when searching. Here is an example:
+This command finds the "free software" phrase in the files of the current directory. It processes the hidden objects too.
+
+If you work on Linux or macOS, prefer the `-R` option instead of `-r`. It forces `grep` to follow [**symbol links**](https://en.wikipedia.org/wiki/Symbolic_link) when searching. Here is an example:
 {line-numbers: false, format: Bash}
 ```
 grep -R "free software" .

manuscript/BashShell/tools.md

@@ -47,7 +47,7 @@ Now we have everything to install MSYS2. Follow these steps for doing it:
 
 4. The next window suggests you to choose the application name for the Windows "Start" menu. Leave it unchanged and click the "Next" button. Then the installation process starts.
 
-4. When the installation finishes, click the "Finish" button. It closes the installer window.
+5. When the installation finishes, click the "Finish" button. It closes the installer window.
 
 You have installed the MSYS2 Unix environment on your hard drive. You can find its files in the `C:\msys64` directory if you did not change the default installation path. Go to this directory and run the `msys2.exe` file. It opens the window where you can work with the Bash shell. Figure 2-4 shows this window.
 

manuscript/answers.md

@@ -655,13 +655,13 @@ Let's perform bit-shifts for the signed two-byte integers. Then you will get the
 0110 0100 0011 0 = 0000 1100 1000 0110 = 3206
 
 * 25649 << 2 = 0110 0100 0011 0001 << 2 =
-10 0100 0011 0001 -> 1001 0000 1100 0100 -> 1110 1111 0011 1100 = -28476
+10 0100 0011 0001 -> 1001 0000 1100 0100 = -28476
 
 * -9154 >> 4 = 1101 1100 0011 1110 >> 4 =
-1101 1100 0011 -> 1111 1101 1100 0011 -> 1000 0010 0011 1101 = -573
+1101 1100 0011 -> 1111 1101 1100 0011 = -573
 
 * -9154 << 3 = 1101 1100 0011 1110 << 3 =
-1 1100 0011 1110 -> 1110 0001 1111 0000 -> 1001 1110 0001 0000 = -7696
+1 1100 0011 1110 -> 1110 0001 1111 0000 = -7696
 ```
 
 Here are the Bash commands for checking the calculations: