docs (level 101): fix typos, punctuation, formatting (#160)

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courses/level101/metrics_and_monitoring/command-line_tools.md

@@ -6,48 +6,48 @@ monitor the system's performance. These tools help you measure and
 understand various subsystem statistics (CPU, memory, network, and so
 on). Let's look at some of the tools that are predominantly used.
 
--   `ps/top `-- The process status command (ps) displays information
+-   **`ps/top`**: The process status command (`ps`) displays information
      about all the currently running processes in a Linux system. The
-     top command is similar to the ps command, but it periodically
+     top command is similar to the `ps` command, but it periodically
      updates the information displayed until the program is terminated.
-     An advanced version of top, called htop, has a more user-friendly
+     An advanced version of top, called `htop`, has a more user-friendly
      interface and some additional features. These command-line
      utilities come with options to modify the operation and output of
      the command. Following are some important options supported by the
-     ps command.
+     `ps` command.
 
-    -   `-p <pid1, pid2,...>` -- Displays information about processes
+    -   `-p <pid1, pid2,...>`: Displays information about processes
          that match the specified process IDs. Similarly, you can use
          `-u <uid>` and `-g <gid>` to display information about
          processes belonging to a specific user or group.
 
-    -   `-a` -- Displays information about other users' processes, as well
+    -   `-a`: Displays information about other users' processes, as well
          as one's own.
 
-    -   `-x` -- When displaying processes matched by other options,
+    -   `-x`: When displaying processes matched by other options,
          includes processes that do not have a controlling terminal.
 
  ![Results of top command](images/image12.png) 
  <p align="center"> Figure 2: Results of top command </p>
 
--   `ss` -- The socket statistics command (ss) displays information
+-   **`ss`**: The socket statistics command (`ss`) displays information
      about network sockets on the system. This tool is the successor of
      [netstat](https://man7.org/linux/man-pages/man8/netstat.8.html),
      which is deprecated. Following are some command-line options
-     supported by the ss command:
+     supported by the `ss` command:
 
-    -   `-t` -- Displays the TCP socket. Similarly, `-u` displays UDP
+    -   `-t`: Displays the TCP socket. Similarly, `-u` displays UDP
          sockets, `-x` is for UNIX domain sockets, and so on.
 
-    -   `-l` -- Displays only listening sockets.
+    -   `-l`: Displays only listening sockets.
 
-    -   `-n` -- Instructs the command to not resolve service names.
+    -   `-n`: Instructs the command to not resolve service names.
          Instead displays the port numbers.
 
 ![List of listening sockets on a system](images/image8.png) <p align="center"> Figure
 3: List of listening sockets on a system </p>
 
--   `free` -- The free command displays memory usage statistics on the
+-   **`free`**: The `free` command displays memory usage statistics on the
      host like available memory, used memory, and free memory. Most often,
      this command is used with the `-h` command-line option, which
      displays the statistics in a human-readable format.
@@ -55,7 +55,7 @@ on). Let's look at some of the tools that are predominantly used.
 ![Memory statistics on a host in human-readable form](images/image6.png) 
 <p align="center"> Figure 4: Memory statistics on a host in human-readable form </p>
 
--   `df --` The df command displays disk space usage statistics. The
+-   **`df`**: The `df` command displays disk space usage statistics. The
      `-i` command-line option is also often used to display
      [inode](https://en.wikipedia.org/wiki/Inode) usage
      statistics. The `-h` command-line option is used for displaying
@@ -65,12 +65,12 @@ on). Let's look at some of the tools that are predominantly used.
 <p align="center"> Figure 5:
  Disk usage statistics on a system in human-readable form </p>
 
--   `sar` -- The sar utility monitors various subsystems, such as CPU
+-   **`sar`**: The `sar` utility monitors various subsystems, such as CPU
      and memory, in real time. This data can be stored in a file
      specified with the `-o` option. This tool helps to identify
      anomalies.
 
--   `iftop` -- The interface top command (`iftop`) displays bandwidth
+-   **`iftop`**: The interface top command (`iftop`) displays bandwidth
      utilization by a host on an interface. This command is often used
      to identify bandwidth usage by active connections. The `-i` option
      specifies which network interface to watch.
@@ -80,22 +80,22 @@ on). Let's look at some of the tools that are predominantly used.
   <p align="center"> Figure 6: Network bandwidth usage by
 active connection on the host </p>
 
--   `tcpdump` -- The tcpdump command is a network monitoring tool that
+-   **`tcpdump`**: The `tcpdump` command is a network monitoring tool that
      captures network packets flowing over the network and displays a
      description of the captured packets. The following options are
      available:
 
-    -   `-i <interface>` -- Interface to listen on
+    -   `-i <interface>`: Interface to listen on
 
-    -   `host <IP/hostname>` -- Filters traffic going to or from the
+    -   `host <IP/hostname>`: Filters traffic going to or from the
          specified host
 
-    -   `src/dst` -- Displays one-way traffic from the source (src) or to
+    -   `src/dst`: Displays one-way traffic from the source (src) or to
          the destination (dst)
 
-    -   `port <port number>` -- Filters traffic to or from a particular
+    -   `port <port number>`: Filters traffic to or from a particular
          port
 
 ![tcpdump of packets on an interface](images/image10.png) 
-<p align="center"> Figure 7: *tcpdump* of packets on *docker0*
+<p align="center"> Figure 7: <code>tcpdump</code> of packets on <code>docker0</code>
 interface on a host </p>