如果值相等时是否触发-gt打击?

我希望我的脚本检查它是否已经在另一个实例中运行:

$ cat test.sh 
#!/bin/bash

ps -ef | grep -v grep | grep -i "test.sh" | grep bash
ps -ef | grep -v grep | grep -i "test.sh" | grep -c bash

if [ `ps -ef | grep -v grep | grep -i "test.sh" | grep -c bash` -gt 1 ]; then echo "There's another instance running."
else echo "Only this instance is running."
fi

但是输出是

$ ./test.sh 
noes   9503  7494  0 09:32 pts/1    00:00:00 /bin/bash ./test.sh
1
There's another instance running.

显然,1不大于1,那么为什么触发if条件?

谢谢