Bash脚本：从shell脚本登录到postgres主页

Question

I have to take a data dump from my postgres database.

How do I log in to the postgres home ? . I have the following script but it doesn't work :

#!/bin/sh$                                                                      
export PASSWORD= something                                                      
echo $PASSWORD | sudo -S su postgres                                                                                                                 
pg_dump somedb > dump.txt+`date +%Y-%m-%d`          

However when I run this script I do not get logged to postgres@gauss:$ at the same time script doesn't throw an error. Is there something I am doing wrong here ?

Answer 1

The reason your script fails is that the line

 echo $PASSWORD | sudo -S su postgres

causes su to fork a subordinate shell. That shell tries to read from the standard input which has already been exhausted by sudo -S in reading the password. When the shell finds no more input (EOF) it exits. The next line of your script then executes as if that quoted line never happened, and therefore runs under your UID.

See j.hloetzek's answer for a much better way to do what you want.

Also the script as pasted has a two syntax errors in it, but you shouldn't use that approach anyway.

Answer 2

您无法将密码传递给sudo命令，但可以在/etc/sudoers允许在没有密码的情况下运行某些命令（请检查确切的语法！）

username YOURUSERNAME = NOPASSWD: /sbin/su postgres