将postgresql结果存储在bash变量中
问题描述：
如何像下面的脚本那样在bash变量上赋予标量postgresql值？
How to atore a scalar postgresql-value on a bash-variable like in script below?
dbname="testlauf"
username="postgres"
vartest='psql -c -d $dbname -U $username -h localhost -p 5432 "SELECT gid FROM testtable WHERE aid='1';"'
echo "$vartest"
我尝试了几种不同的著作，但似乎没有任何效果。
I tried several different writings, but nothing seems to work. Thanks in advance.
答
将 -c 选项放在其前面参数-查询。注意，还可以使用附加的 -t 选项仅获取元组值。当然，请使用反引号（`）运算符。
Put the -c option just before its argument - the query. Mind also using the additional -t option to get just the tuple value. And of course, use the backticks (`) operator.
使用 -X 还建议使用>选项，因为有时 .psqlrc 文件可能会添加一些冗余输出，以及 -A 选项，该选项将禁用列对齐（空格）。
Using the -X option is also recommended, as sometimes a .psqlrc file might add some redundant output, as well as the -A option, which disables column aligning (whitespaces).
vartest=`psql -X -A -d $dbname -U $username -h localhost -p 5432 -t -c "SELECT gid FROM testtable WHERE aid='1'"`