Begin by exporting the required data from your Teradata database. You can accomplish this using the `BTEQ` utility to run SQL queries and save the output to a file. Use the `EXPORT` command to specify the output file format (e.g., CSV). For example:
```sql
.LOGON your_teradata_server/username,password;
.EXPORT FILE = 'data_export.csv';
SELECT FROM your_table;
.EXPORT RESET;
.LOGOFF;
```

After exporting the data, ensure that the data format is compatible with Postgres. Verify the CSV file for any data discrepancies or formatting issues. Adjust delimiters, line endings, and quote characters if necessary to match Postgres's expected format.

Transfer the CSV file to the server where your Postgres database is hosted. Use secure file transfer methods like `scp` or `sftp` to ensure the data is securely moved. For example:
```bash
scp data_export.csv user@postgres_server:/path/to/directory
```

Before importing the data, create a table in the Postgres database that matches the schema of the exported data. Use `CREATE TABLE` statements to define columns with appropriate data types and constraints. For example:
```sql
CREATE TABLE your_table (
column1 INTEGER,
column2 VARCHAR(255),
column3 DATE
);
```

Use the `COPY` command in Postgres to import the data from the CSV file into the newly created table. This command reads the file and populates the table efficiently. For example:
```sql
COPY your_table FROM '/path/to/directory/data_export.csv'
DELIMITER ',' CSV HEADER;
```

After the import, validate the data in the Postgres table to ensure accuracy. Run queries to check record counts, data integrity, and any potential truncation or formatting issues. Use SQL queries like:
```sql
SELECT COUNT() FROM your_table;
```

If this data transfer needs to occur regularly, consider automating the process using shell scripts or cron jobs. Create a script that combines the above steps and schedule it to run at defined intervals using `cron`:
```bash
#!/bin/bash
# Run BTEQ to export data
# Transfer file
# Run psql to import data
# Add cron job
```

This guide outlines a manual approach to moving data between Teradata and Postgres. Each step should be adapted to the specific needs and configurations of your systems.