A Collection of Shell Scripts/Commands

collection.sh

# convert text files to all lower case
$ tr '[:upper:]' '[:lower:]' < input.txt > output.txt
 
# Convert Data Stored in a Shell Variable From UPPPER to lowercase
$ echo $VAR_NAME | tr '[:upper:]' '[:lower:]'
# Convert Data Stored in a Shell Variable From lowercase to UPPER
$ echo $VAR_NAME | tr '[:lower:]' '[:upper:]'

# job control:
# ctrl+z - suspend a job and put into background
# fg - brings a background job
fg
# bg - list all the background jobs
# jobs - list all the background/foreground jobs, (-l to list with pid)
jobs -l

# add launchpad apps to ubuntu software sources
sudo add-apt-repository ppa:<user>/<ppa-name>

## curl for HTTP requests ###
curl -D - -X POST -d "key=value&key1=value1" http://localhost/someurl
# "-D -" is dump response header to a file, "-" meaning to console
# "-X POST" is set request method
# "-d" or "--data is for post request data, alternatives:
#     "-d @file" - the request content is in the file
#     "--data-ascii" - default 
#     "--data-binary key@binaryfile" - raw data that loads binary file of "binaryfile" as for key "key"


### User & Group ###
# add user to an existing group
usermod -a -G ftp terryoy
# change user's primary group
usermod -g www terryoy
# create user with primary group
useradd -g developers terryoy
# check user's group
id terryoy

mount.sh

#!/bin/bash

# script to mount a virtualbox vdi file to a path
# e.g.: sudo ./mount.sh xxx.vdi vdisk
mkdir .$2 
vdfuse -raf $1 .$2
mkdir $2
mount .$2/Partition1 $2

unmount.sh

#!/bin/bash

# the script unmount and remove the vdisk which works together with mount.sh
# e.g.: sudo ./unmount.sh vdisk
umount $1
umount .$1
rm -ir $1 .$1