Teo Lopez

File Permission Modes

September 2, 2016 by Teo Lopez Leave a Comment

  7       5     5
 user   group  world
 r+w+x  r+x    r+x
 4+2+1  4+0+1  4+0+1  = 755

The permission mode is computed by adding up the following values for the user, the file group, and for everyone else. The diagram shows how.

Read 4 – Allowed to read files
Write 2 – Allowed to write/modify files
eXecute 1 – Read/write/delete/modify/directory

  7       4      4
 user   group  world
 r+w+x    r      r
 4+2+1  4+0+0  4+0+0  = 744

Example Permission Modes

See full list 0000 to 0777.
Mode	Str Perms	Explanation
0477	-r–rwxrwx	owner has read only (4), other and group has rwx (7)
0677	-rw-rwxrwx	owner has rw only(6), other and group has rwx (7)
0444	-r–r–r–	all have read only (4)
0666	-rw-rw-rw-	all have rw only (6)
0400	-r——–	owner has read only(4), group and others have no permission(0)
0600	-rw——-	owner has rw only, group and others have no permission
0470	-r–rwx—	owner has read only, group has rwx, others have no permission
0407	-r—–rwx	owner has read only, other has rwx, group has no permission
0670	-rw-rwx—	owner has rw only, group has rwx, others have no permission
0607	-rw—-rwx	owner has rw only, group has no permission and others have rwx

View Permissions, Users, and Group

To view the permissions and who the user owner is type in the following command in terminal:

ls -l

This will give you the results in the image below. (notes have been added to describe what each column is for.

Format USB drive for Mac and Windows using El Capitan

August 18, 2016 by Teo Lopez Leave a Comment

Insert the USB drive and open up Disk Utility.
Click on the actual drive name, not the partition/s.
Click Erase.
1. Select whatever you want the name to be in the name field.
2. Select MS-DOS (FAT) or ExFAT depending on the Win file system you want.
3. Select Master Boot Record for the scheme.
Click Erase.
Once done, unmount and try it on your windows machine. Should work.

Copying multiple specific files from one folder to another

July 12, 2016 by Teo Lopez Leave a Comment

There are several ways you could achieve this. The easiest I have seen is to use the following.
cp /home/usr/dir/{file1,file2,file3,file4} /home/usr/destination/

cp /home/usr/dir/{file1,file2,file3,file4} /home/usr/destination/

The syntax uses the cp command followed by the path to the directory the desired files are located in with all the files you wish to copy wrapped in brackets and separated by commas.

Make sure to note that there are no spaces between the files. The last part of the command, /home/usr/destination/, is the directory you wish to copy the files into.

or if the all the files have the same prefix but different endings you could do something like this:
cp /home/usr/dir/file{1..4} ./
Where file1,file2,file3 and file4 would be copied.

How to locate your machine name PC or Mac

April 15, 2016 by Teo Lopez Leave a Comment

Follow the instructions below to locate your device name based on platform.

Windows XP:

Right-Click My Computer and Select Properties
Click the Computer Name tab.
Your Computer Name is listed under Full Computer Name.

Windows Vista:

Open System by clicking the Start button.
Click on Control Panel > System and Maintenance, and then clicking System.
Your Computer Name is listed under Full Computer Name.

Windows 7:

Open System by clicking the Start button.
Right-click on Computer, and then clicking Properties
Under Computer name, domain, and workgroup settings, you can find your computer name, and its full computer name if your computer is on a domain.

Windows 8:

Hover the mouse at the top right
Click the settings cog > PC info.
Under Computer name, domain, and workgroup settings, you can find your computer name, and its full computer name if your computer is on a domain.

Windows 8.1 and 10:

Right click on the Start button
Click System
Under Computer name, domain, and workgroup settings, you can find your computer name, and its full computer name if your computer is on a domain.

Mac OS X 10.4 and later:

Launch your System Preferences.
Click on the Sharing pane.
Your Computer Name is listed at the top of the pane.

iOS

Launch your Settings app
Press General and then press About.
Your iOS device name will be at the top left of the screen.

Simple MySQL Commands Cheat sheet

April 8, 2016 by Teo Lopez Leave a Comment

Commands

Access monitor: mysql -u [username] -p; (will prompt for password)

Show all databases: show databases;

Access database: mysql -u [username] -p [database] (will prompt for password)

Create new database: create database [database];

Select database: use [database];

Show all tables: show tables;

Show table structure: describe [table];

Create new table with columns: CREATE TABLE [table] ([column] VARCHAR(120), [another-column] DATETIME);

Adding a column: ALTER TABLE [table] ADD COLUMN [column] VARCHAR(120);

Adding a column with an unique, auto-incrementing ID: ALTER TABLE [table] ADD COLUMN [column] int NOT NULL AUTO_INCREMENT PRIMARY KEY;

Inserting a record: INSERT INTO [table] ([column], [column]) VALUES ('[value]', [value]');

MySQL function for datetime input: NOW()

Selecting records: SELECT * FROM [table];

Explain records: EXPLAIN SELECT * FROM [table];

Selecting parts of records: SELECT [column], [another-column] FROM [table];

Counting records: SELECT COUNT([column]) FROM [table];

Counting and selecting grouped records: SELECT *, (SELECT COUNT([column]) FROM [table]) AS count FROM [table] GROUP BY [column];

Selecting specific records: SELECT * FROM [table] WHERE [column] = [value]; (Selectors: <, >, !=; combine multiple selectors with AND, OR)

Select records containing [value]: SELECT * FROM [table] WHERE [column] LIKE '%[value]%';

Select records starting with [value]: SELECT * FROM [table] WHERE [column] LIKE '[value]%';

Select records starting with val and ending with ue: SELECT * FROM [table] WHERE [column] LIKE '[val_ue]';

Select a range: SELECT * FROM [table] WHERE [column] BETWEEN [value1] and [value2];

Select with custom order and only limit: SELECT * FROM [table] WHERE [column] ORDER BY [column] ASC LIMIT [value];(Order: DESC, ASC)

Updating records: UPDATE [table] SET [column] = '[updated-value]' WHERE [column] = [value];

Deleting records: DELETE FROM [table] WHERE [column] = [value];

Delete all records from a table (without dropping the table itself): DELETE FROM [table]; (This also resets the incrementing counter for auto generated columns like an id column.)

Removing table columns: ALTER TABLE [table] DROP COLUMN [column];

Deleting tables: DROP TABLE [table];

Deleting databases: DROP DATABASE [database];

Custom column output names: SELECT [column] AS [custom-column] FROM [table];

Export a database dump (more info here): mysqldump -u [username] -p [database] > db_backup.sql

Use --lock-tables=false option for locked tables (more info here).

Import a database dump (more info here): mysql -u [username] -p -h localhost [database] < db_backup.sql

Logout: exit;

Users functions

List all users: SELECT User,Host FROM mysql.user;

Create new user: CREATE USER 'username'@'localhost' IDENTIFIED BY 'password';

Grant ALL access to user for * tables: GRANT ALL ON database.* TO 'user'@'localhost';

Find out the IP Address of the Mysql Host

SHOW VARIABLES WHERE Variable_name = 'hostname'; (source)