From 7dad690a5fd1124a3325e6d36af95cc75944e3a9 Mon Sep 17 00:00:00 2001
From: tomit4 <mosssap@gmail.com>
Date: Sat, 7 May 2022 16:11:26 -0700
Subject: [PATCH] copied table 5.1, which covers basic shell built-in variables

---
 .../shell_built_in_variables.txt                   | 14 ++++++++++++++
 1 file changed, 14 insertions(+)
 create mode 100644 unix_programming_environment/shell_built_in_variables.txt

diff --git a/unix_programming_environment/shell_built_in_variables.txt b/unix_programming_environment/shell_built_in_variables.txt
new file mode 100644
index 00000000..8757d10a
--- /dev/null
+++ b/unix_programming_environment/shell_built_in_variables.txt
@@ -0,0 +1,14 @@
+-------------------------- Table 5.1 --------------------------
+
+$#      the number of arguments
+$*      all arguments to shell
+$@      similar to $*; see Section 5.7
+$-      options supplied to shell
+$?      return value of the last command executed
+$$      process-id of the shell
+$!      process-id of the last command started with &
+$HOME   default argument for cd command
+$IFS    list of characters that separate words in arguments
+$PATH   list of directories to search for commands
+$PS1    prompt string, default '$ '
+$PS2    prompt string for continued command line, default '> '