more bash examples

shell_scripts/lessons/TRICKS.md

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+Wild Cards
+----------
+
+Use *, ? (for one char), and [abc] for a series of options. Example:
+
+$ ls [abc]*
+
+
+More commands on one line
+-------------------------
+
+Use ;
+$ date;who
+
+
+Redirection of Standard output/input
+-----------------------------------
+
+>, >>, <
+
+Examples:
+
+$ sort < filename > sorted_names
+
+
+Pipes
+-----
+A pipe is nothing but a temporary storage place where the output of one command is stored and then passed as the input for second command.
+
+
+Processes and PID
+-----------------
+An instance of running command is called process and the number printed by shell is called process-id (PID), this PID can be use to refer specific running process.
+
+ps - show current running
+kill {PID} - kill process
+kill 0 - stop all processes except shell
+& - background process
+ps aux - display the owner of the processes along with the processes
+ps -ag - get information of all running processes
+ps ax | grep processes-you-want-to-see
+top - see currently running processes and other information like memory and CPU
+pstree - display a tree of processes
+
+
+
+Useful Cmds:
+------------
+
+List size of folders
+$ du -sh *
+
+

shell_scripts/lessons/arguments.ssh

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+#! /bin/bash
+# script to test for loop and arguments
+
+if [ $# -eq 0 ]
+  then
+  echo "Error - Number missing form command line argument"
+  echo "Syntax : $0 number"
+  echo "Use to print multiplication table for given number"
+  exit 1
+fi
+n=$1
+for i in 1 2 3 4 5 6 7 8 9 10
+do
+  echo "$n * $i = `expr $i \* $n`"
+done

shell_scripts/lessons/cheesboard.sh

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+#! /bin/bash
+# script to print a chessboard
+
+for (( i = 1; i <= 9; i++ ))
+do
+  for (( j = 1; j <= 9; j++))
+  do
+    tot=`expr $i + $j`
+    tmp=`expr $tot % 2`
+    if [ $tmp -eq 0 ]; then
+      echo -e -n "\033[47m  "
+    else
+      echo -e -n "\033[40m  "
+    fi
+  done
+  echo -e -n "\033[40m" # set to black
+  echo"" # print new line
+done

shell_scripts/lessons/echo_cmds.sh

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+#! /bin/bash
+echo "The echo commands are (use echo -e):"
+echo
+echo -e "\a alert "
+echo -e "\n new line"
+echo -e "\t horizontal tab"
+echo -e "\c suppress trailing line"
+echo -e "\r carriage return"
+echo -e "\b backspace"

shell_scripts/lessons/if_example.sh

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+#! /bin/bash
+#
+#Syntax:
+#  if condition
+#  then
+#    if condition
+#    then
+#      .....
+#      ..
+#     do this
+#    else
+#      ....
+#      ..
+#      do this
+#    fi
+#  else
+#    ...
+#    .....
+#    do this
+#  fi
+#
+# You can also use
+#   elif
+#       ...
+#   then
+#
+#
+
+
+echo "Here an example of how to use if condition for numbers:"
+echo
+echo "Type a number from 1 to 10:"
+read number
+if test $number -gt 5
+then
+echo "This number is larger than 5"
+fi
+if test $number -lt 5
+then
+echo "This number is smaller than 5"
+fi
+echo
+echo "Operators are: -eq, -ne, -lt, -gt, -ge"
+echo
+echo "****************************************************"
+echo
+echo "Here an example of how to use if condition for strings:"
+echo
+echo "Type a number your name:"
+read name
+if test $name != "john"
+then
+echo "Your name is not John, its $name"
+else
+echo "Your name is john! What the odds?"
+fi
+echo
+echo "Operators are: =, !=, -n (not null, exist), -z null (exist)"
+echo
+echo "****************************************************"
+echo
+echo "Here an example of how to use if condition for files:"
+echo
+echo "Operators are: -s (non empty), -f (exist), -d (directory exist), -w (writeable), -r (read-only), -x (executable)"
+echo
+echo "****************************************************"
+echo
+echo "Here an example of how to use logical operators:"
+echo
+echo "Operators are: ! (NOT), -a (AND), -o (OR)"

shell_scripts/lessons/inputs.sh

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+#! /bin/bash
+echo "We use read to read an input"
+echo
+echo "Type your name: "
+read fname
+echo "You name is $fname"
+echo

shell_scripts/lessons/linux_console.sh

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+#! /bin/bash
+echo "The Linux Console variables are:"
+echo
+echo "\33 is the escape char, to take an action. Ex: using \033[34m:"
+echo -e "\033[34m Hello! \033[0m"
+echo
+echo " [ is the start, 34 the parameter, m is the letter (action)"
+echo " letters can be h, l, m, q, s, u..."
+echo " parameters can be 0, 1 (bold), 2 (dim intensity), 5 (blink), 7 (reverse), 11, 25, 27, 30-27 (colors), 4047 (bkgd colors)..."
+echo
+echo "For example:"
+echo -e "\033[5m Hey! \033[0m"
+echo
+echo "Now, quotes... the black quote is used to execute a cmd (\`cmd\`)"
+echo

shell_scripts/lessons/shell_variables.sh

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+#! /bin/bash
+echo "The variable of the system are:"
+echo
+echo "BASH_VERSION: " $BASH_VERSION
+echo "LOGNAME: " $LOGNAME
+echo "OSTYPE: " $OSTYPE
+echo "PATH: " $PATH
+echo "PWD: " $PWD
+echo "USERNAME: " $USERNAME
+echo
+echo "Linux distribution, name, arch: $ uname -a"
+echo