为什么带有 -c 选项的 grep 总是在 ssh 上显示 0

Question

I have a script on three different servers. The basics are that script checks for a certain file on its system and if the file is not there then it will ssh to the other servers and run the same script. The check is run via;

If [[ $(ls ${folder} | grep -c ${file}) -gt 0 ]]; then "do stuff with the files"; else "ssh to other server and check again"; fi

It wasnt giving output when the information was on a remote server. So I ran the check on a server I knew had the files and it worked. However when i would try and run it remotely, the file count would be 0.

I changed it from grep to wc -l and then it worked. I'm wondering if anybody knows why grep -c works locally but with ssh

Answer 1

It 'if' doesn't work like that. If you want to check the existence of a file, you must use this:

[ -f ${file} ]