- Run the following command:
sudo dpkg -i <DEBIAN_PACKAGE>
Token Description DEBIAN_PACKAGE A Debian package that normally has deb extension. - Fix the broken dependencies by running the following command:
sudo apt-get install -f
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| Command | Description |
|---|---|
| postqueue -p | Display the queue |
| postcat -vq <QUEUE_ID> | View the content of the email |
| postsuper -d ALL | Remove all emails |
| postsuper -d <QUEUE_ID> | Remove a particular email |
| postqueue -i <QUEUE_ID> | Attempt to send one particular email |
| Token | Description |
| QUEUE_ID | Can be identified by displaying the queue. |
Syntax
To sync some of your local directories to another local directory, you can use the following syntax:
rsync -av -L --delete <DIR1>[[ <DIR2>] <DIRn>] <DESTINATION_DIR>
| Token | Description |
| DIR1, DIR2, DIRn | These are the local directories you've wanted to be synced. Only DIR1 is required and the rest are optional. |
| DESTINATION_DIR | The destination directory on the remote machine. |
Example
rsync -av -L --delete /var/log/ /data/log/
| Variable | Description | Possible Values |
|---|---|---|
| GIT_CURL_VERBOSE | Tells Git to emit all the messages generated by that library. This is similar to doing curl -v on the command line. | 1 |
| GIT_SSL_NO_VERIFY | Tells Git not to verify SSL certificates. | true |
| GIT_TRACE | Controls general traces | 1, 2 or true |
| GIT_TRACE_PACKET | Enables packet-level tracing for network operations. | true |
- Execute the following command:
ssh-keygen -t ed25519
- Distribute the public key using the following syntax:
ssh-copy-id -i ~/.ssh/id_ed25519.pub <USER>@<HOST>
Token Description USER A valid user on the host computer. HOST The host that has an active ssh service. If ssh-copy-id command doesn't work, you can directly append the content of the id_ed25519.pub file to the ~/.ssh/authorized_keys file (i.e. create this file if it doesn't exists) of the target <USER> on the target <HOST>.
Create a new alias for postfix service by updating the following file:
/etc/aliases
Each entry in the file must have the following syntax:
<ALIAS>: <USER1>[[, <USER2>], <USERn>]
| Token | Description |
| ALIAS | The desired email alias. |
| USER1, USER2, USERn | USER1 is required and the rest are optional. Each user must be delimited by a comma.
The target user of the alias must be a valid user of the system with a home directory. |
Example:
postmaster: root
After updating the file, you must execute the following command:
sudo newaliases
- Add the following dependencies to your build.gradle file:
compile group: 'org.apache.derby', name: 'derby', version: '10.15.1.3' compile group: 'org.apache.derby', name: 'derbyshared', version: '10.15.1.3'
- Add the following entries to your module-info.java file:
requires org.apache.derby.engine; requires org.apache.derby.commons; requires java.sql;
- In your Java class, you can create a connection like the following:
final String DATABASE_NAME = "sample_table"; String connectionURL = String.format("jdbc:derby:%s;create=true", DATABASE_NAME); connection = DriverManager.getConnection(connectionURL); - Do your needed database operations with the connection (e.g. create table, execute a query, or call a stored procedure.).
- When your done using the connection, close the connection and shutdown the Derby engine like the following:
connection.close(); boolean gotSQLExc = false; try { //shutdown all databases and the Derby engine DriverManager.getConnection("jdbc:derby:;shutdown=true"); } catch (SQLException se) { if ( se.getSQLState().equals("XJ015") ) { gotSQLExc = true; } } if (!gotSQLExc) { System.out.println("Database did not shut down normally"); }A clean shutdown always throws SQL exception XJ015, which can be ignored.
Values can become a valid record source for select statement if the values has table alias and column names as follows:
SELECT dummy_table.*
FROM (VALUES ('record1'),
('record2'),
('record3'),
('record4'),
('record5'),
('record6'),
('record7'),
('record8'),
('record9')) dummy_table (column1)
From the preceding select statement, the dummy_table is the table alias and the column name is column1.
Use the following command to create a detached ASCII signature:
gpg --armor --output <ASC_FILE> --detach-sig <FILE_TO_SIGN>
Import Keys from Keyserver
Run the following command:
gpg --receive-keys <KEY_ID>
Showing the Fingerprints
Run the following command:
gpg --fingerprint <KEY_ID>
Verifying a File with ASCII Key
- Download the detach asc <ASC_FILE> file associated to the file.
- Download the signed file <SIGNED_FILE> file.
- Use the following command for verification:
gpg --verify <ASC_FILE> <SIGNED_FILE>
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