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Basic Shell Scripting
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#! /bin/bash | |
# ECHO COMMAND | |
# echo Hello World! | |
# VARIABLES | |
# Uppercase by convention | |
# Letters, numbers, underscores | |
NAME="Bob" | |
# echo "My name is $NAME" | |
# echo "My name is ${NAME}" | |
# USER INPUT | |
# read -p "Enter your name: " NAME | |
# echo "Hello $NAME, nice to meet you!" | |
# SIMPLE IF STATEMENT | |
# if [ "$NAME" == "Brad" ] | |
# then | |
# echo "Your name is Brad" | |
# fi | |
# IF-ELSE | |
# if [ "$NAME" == "Brad" ] | |
# then | |
# echo "Your name is Brad" | |
# else | |
# echo "Your name is NOT Brad" | |
# fi | |
# ELSE-IF (elif) | |
# if [ "$NAME" == "Brad" ] | |
# then | |
# echo "Your name is Brad" | |
# elif [ "$NAME" == "Jack" ] | |
# then | |
# echo "Your name is Jack" | |
# else | |
# echo "Your name is NOT Brad or Jack" | |
# fi | |
# COMPARISON | |
# NUM1=31 | |
# NUM2=5 | |
# if [ "$NUM1" -gt "$NUM2" ] | |
# then | |
# echo "$NUM1 is greater than $NUM2" | |
# else | |
# echo "$NUM1 is less than $NUM2" | |
# fi | |
######## | |
# val1 -eq val2 Returns true if the values are equal | |
# val1 -ne val2 Returns true if the values are not equal | |
# val1 -gt val2 Returns true if val1 is greater than val2 | |
# val1 -ge val2 Returns true if val1 is greater than or equal to val2 | |
# val1 -lt val2 Returns true if val1 is less than val2 | |
# val1 -le val2 Returns true if val1 is less than or equal to val2 | |
######## | |
# FILE CONDITIONS | |
# FILE="test.txt" | |
# if [ -e "$FILE" ] | |
# then | |
# echo "$FILE exists" | |
# else | |
# echo "$FILE does NOT exist" | |
# fi | |
######## | |
# -d file True if the file is a directory | |
# -e file True if the file exists (note that this is not particularly portable, thus -f is generally used) | |
# -f file True if the provided string is a file | |
# -g file True if the group id is set on a file | |
# -r file True if the file is readable | |
# -s file True if the file has a non-zero size | |
# -u True if the user id is set on a file | |
# -w True if the file is writable | |
# -x True if the file is an executable | |
######## | |
#CASE STATEMENT | |
# read -p "Are you 21 or over? Y/N " ANSWER | |
# case "$ANSWER" in | |
# [yY] | [yY][eE][sS]) | |
# echo "You can have a beer :)" | |
# ;; | |
# [nN] | [nN][oO]) | |
# echo "Sorry, no drinking" | |
# ;; | |
# *) | |
# echo "Please enter y/yes or n/no" | |
# ;; | |
# esac | |
# SIMPLE FOR LOOP | |
# NAMES="Brad Kevin Alice Mark" | |
# for NAME in $NAMES | |
# do | |
# echo "Hello $NAME" | |
# done | |
# FOR LOOP TO RENAME FILES | |
# FILES=$(ls *.txt) | |
# NEW="new" | |
# for FILE in $FILES | |
# do | |
# echo "Renaming $FILE to new-$FILE" | |
# mv $FILE $NEW-$FILE | |
# done | |
# WHILE LOOP - READ THROUGH A FILE LINE BY LINE | |
# LINE=1 | |
# while read -r CURRENT_LINE | |
# do | |
# echo "$LINE: $CURRENT_LINE" | |
# ((LINE++)) | |
# done < "./new-1.txt" | |
# FUNCTION | |
# function sayHello() { | |
# echo "Hello World" | |
# } | |
# sayHello | |
# FUNCTION WITH PARAMS | |
# function greet() { | |
# echo "Hello, I am $1 and I am $2" | |
# } | |
# greet "Brad" "36" | |
# CREATE FOLDER AND WRITE TO A FILE | |
# mkdir hello | |
# touch "hello/world.txt" | |
# echo "Hello World" >> "hello/world.txt" | |
# echo "Created hello/world.txt" |
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