Showing posts with label bash. Show all posts
Showing posts with label bash. Show all posts

Thursday, 31 December 2015

Bash - basic script for requesting input from the user

As mentioned in this post, my know-how of Bash scripting is pretty nil so I've been skimming through this guide the last few days to get to grips with the basic concepts. I've put together this basic script as a reminder to myself for future reference of how to request and parse input from the user:

#!/bin/bash

echo "Enter the word that you'd like to add to the dictionary and then press [Enter]."

read WORD

PATH_DICTIONARY="/Users/adil/Downloads/MyDictionary.txt"
COUNT=`grep -c "^$WORD$" $PATH_DICTIONARY`

if [ $COUNT -gt 0 ]
then echo "Word is already contained in the dictionary."; exit;
fi

echo "\$COUNT = $COUNT"

echo "Adding $WORD to the dictionary..."

echo "$WORD" >> $PATH_DICTIONARY

echo "Done"

Bash - basic script for checking positional params

My know-how of Bash scripting is pretty nil so I've been skimming through this guide the last few days to get to grips with the basic concepts. I've put together this basic script as a reminder to myself for future reference of how to pass in and parse positional params in a script:

#!/bin/bash

if [ $# -lt 2 ];
then echo "Must pass in at least two params."; exit 1;
fi

#set -x
GREETING="Hello"
echo "$GREETING $USER"
#set +x

echo ""
echo "\$0 = $0"
echo "\$1 = $1"
echo "\$2 = $2"
echo ""

[ -f $0 ] && (echo "File $0 exists.";) || (echo "File $0 doesn't exist.";)

echo ""

if [ $1 -eq $2 ]; then
echo "The value of \$1 is equal to the value of \$2.";
elif [ $1 -lt $2 ]; then
echo "The value of \$1 is less than the value of \$2.";
else echo "The value of \$1 is greater than the value of \$2.";
fi

echo ""

AREA=$[$1 * $2]
echo "\$AREA = \$1 * \$2 = $AREA"

case $AREA in
([-][0-9]*)
    echo "The value of \$AREA is negative.";;
([0-9])
    echo "The value of \$AREA is < 10.";;
([1-9][0-9])
    echo "The value of \$AREA is < 100.";;
*)
    echo "The value of \$AREA is >= 100.";;
esac

echo ""
echo "Goodbye $USER"

If I run this script as follows: bash MyScript.sh, then I'll see this output:

Must pass in at least two params.

If, however, I run this script as follows: bash MyScript.sh 5 4, then I'll see this output:

Hello adil

$0 = MyScript.sh
$1 = 5
$2 = 4

File MyScript.sh exists.

The value of $1 is greater than the value of $2.

$AREA = $1 * $2 = 20
The value of $AREA is < 100.

Goodbye adil

That's it. That's a basic script which demonstrates how to perform some conditional checks on positional params passed into a script.