MySQL后台查询：使用nohup执行后台查询后如何存储查询结果

Got it, let's sort this out for you! When you run a command with nohup and background it with &, the default behavior sends standard output to a file named nohup.out—but if you want more control over where your query results end up, here are three reliable methods:

1. Redirect Output Directly in the Command #

The simplest way is to explicitly redirect the command's output (and error messages) to a file of your choice. Modify your original command like this:

nohup mysql -u <user> -h <host> -p<password> db_name -e "Select * from table_name;" > query_results.txt 2>&1 &

• The > query_results.txt part tells the shell to send all standard output (your query results) to query_results.txt.
• 2>&1 redirects standard error (like connection failures or SQL errors) to the same file, so you can debug issues if the query fails.

2. Use MySQL's INTO OUTFILE Clause #

For more control over the output format (like CSV with custom delimiters), let MySQL handle writing the file directly. Adjust your SQL query like this:

nohup mysql -u <user> -h <host> -p<password> db_name -e "SELECT * FROM table_name INTO OUTFILE '/tmp/query_results.csv' FIELDS TERMINATED BY ',' ENCLOSED BY '\"' LINES TERMINATED BY '\n';" &

A few things to note here:

• You'll need the FILE privilege assigned to your MySQL user to use this.
• The target path (like /tmp/) must be writable by the MySQL server process—system temporary directories are usually safe choices.
• This method lets you define exactly how the output is formatted, which is great for importing the results into other tools later.

3. Check the Default nohup.out File #

If you didn't redirect output, nohup automatically saves stdout and stderr to nohup.out in your current working directory. You can view this file with:

cat nohup.out
# Or follow it in real-time if the query is still running:
tail -f nohup.out

Just keep in mind: running multiple nohup commands will overwrite this file, so it's better to use explicit redirection if you need to keep results long-term.

Quick Security Tip #

Storing your password in plaintext in the command line is risky—it shows up in shell history and process lists. Instead, create a dedicated config file (e.g., ~/.mysql_config.cnf):

[client]
user = your_username
password = your_password
host = your_host

Then set strict permissions on it:

chmod 600 ~/.mysql_config.cnf

And modify your nohup command to use this file:

nohup mysql --defaults-extra-file=~/.mysql_config.cnf db_name -e "Select * from table_name;" > query_results.txt 2>&1 &

This keeps your password secure while still letting you run the command in the background.

内容的提问来源于stack exchange，提问作者Jazzyb