New gemstone - bash script stub

* A non-exhaustive script that contains some commonly used routines.

Author: sspencerwire

docs/gemstones/bash_stub.md

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+---
+title: bash - Script Stub
+author: Steven Spencer
+---
+
+# Bash - Script Stub
+
+Where I was previously employed, we had an ace programmer who knew a bunch of languages. He was also the go-to guy when you had questions on how to accomplish something with a script. He finally created a little stub which had some examples of how to do things that you could just strip out and edit as needed. Eventually, I got good enough at these routines that I didn't have to look at the stub, but it was a good learning tool, and something that others may find useful.
+
+## The Actual Stub
+
+The stub is well documented. Keep in mind that this is by no means an exhaustive script! There are a lot more routines that could be added. If **you** have examples that would fit nicely into this stub, then please feel free to add some changes:
+
+```
+#!/bin/sh
+
+# By exporting the path, this keeps you from having to enter full paths for commands that exist in those paths:
+
+export PATH="$PATH:/bin:/usr/bin:/usr/local/bin"
+
+# Determine and save absolute path to program directory.
+# When done will be in same directory as script:
+
+PGM=`basename $0`				# Name of the program
+CDIR=`pwd`					# Save directory program was run from
+
+PDIR=`dirname $0`
+cd $PDIR
+PDIR=`pwd`
+
+# If program accepts filenames as arguments, this will put us back where we started.
+# (Needed so references to files using relative paths work.):
+
+cd $CDIR
+
+# Use this if script must be run by certain user:
+
+runby="root"
+iam=`/usr/bin/id -un`
+if [ $iam != "$runby" ]
+then
+	echo "$PGM : program must be run by user \"$runby\""
+	exit
+fi
+
+# Check for missing parameter.
+# Display usage message and exit if it is missing:
+
+if [ "$1" = "" ]
+then
+	echo "$PGM : parameter 1 is required"
+	echo "Usage: $PGM param-one"
+	exit
+fi
+
+# Prompt for data (in this case a yes/no response that defaults to "N"):
+
+/bin/echo -n "Do you wish to continue? [y/N] "
+read yn
+if [ "$yn" != "y" ] && [ "$yn" != "Y" ]
+then
+	echo "Cancelling..."
+	exit;
+fi
+
+# If only one copy of your script can run at a time use this block of code.
+# Check for lock file.  If it doesn't exist create it.
+# If it does exist display error message and exit:
+
+LOCKF="/tmp/${PGM}.lock"
+if [ ! -e $LOCKF ]
+then
+	touch $LOCKF
+else
+	echo "$PGM: cannot continue -- lock file exists"
+	echo
+	echo "To continue make sure this program is not already running, then delete the"
+	echo "lock file:"
+	echo
+	echo "    rm -f $LOCKF"
+	echo
+	echo "Aborting..."
+	exit 0
+fi
+
+script_list=`ls customer/*`
+
+for script in $script_list
+do
+	if [ $script != $PGM ]
+	then
+		echo "./${script}"
+	fi
+done
+
+# Remove the lock file
+
+rm -f $LOCKF
+```
+
+## Conclusion
+
+Scripting is a System Administrators friend. Being able to quickly do certain tasks in a script streamlines process completion. While by no means an exhaustive set of script routines, this stub offers some common usage examples.