mjhjmtu

This is strange. I want only to grep line containing /run. But it returning other lines too.

 [root@s5 ~]# df -h | grep -w "tm"
 [root@s5 ~]# df -h | grep -w "tmpfs"
 tmpfs 489M 0 489M 0% /dev/shm
 tmpfs 489M 6.8M 483M 2% /run
 tmpfs 489M 0 489M 0% /sys/fs/cgroup
 tmpfs 98M 0 98M 0% /run/user/1001
 tmpfs 98M 0 98M 0% /run/user/0
 [root@s5 ~]# df -h | grep -w "tmpf"
 [root@s5 ~]# df -h | grep -w "/run"
 tmpfs 489M 6.8M 483M 2% /run
 tmpfs 98M 0 98M 0% /run/user/1001
 tmpfs 98M 0 98M 0% /run/user/0

man grep:

-w, --word-regexp
Select only those lines containing matches that form whole words. The test is that the matching substring must either be at the beginning of the line, or preceded by a non-word constituent character. Similarly, it must be either at the end of the line or followed by a non-word constituent character. Word-constituent characters are letters, digits, and the underscore.

Works as expected, I say. If your intention is to get only the first match you should use

$ df -h | grep -w "/run$"