[root@docker tmp]# grep -oE "[[0-9].+]" logfile
[113a6d9e-7b06-42c6-a52b-7a4e4d2e216c]
[113a6d9e-7b06-42c6-a52b-7a4e4d2e216c]
[root@docker tmp]#

$ grep -oP "(?<=[)[0-9].+(?=])" logfile
113a6d9e-7b06-42c6-a52b-7a4e4d2e216c
113a6d9e-7b06-42c6-a52b-7a4e4d2e216c

$ cat a.txt
test hello..[113a6d9e-7b06-42c6-a52b-7a4e4d2e216c]... this is
te [113a6d9e-7b06-42c6-a52b-7a4e4d2e216c].  this  is hello

$ grep -oP '(?<=[)[^]]*' a.txt
113a6d9e-7b06-42c6-a52b-7a4e4d2e216c
113a6d9e-7b06-42c6-a52b-7a4e4d2e216c

grep -oE "[[0-9].+]" logfile | cut -d'[' -f2 | cut -d']' -f1

$ grep -oE "[[0-9].+]" logfile | tr -d '[]'
113a6d9e-7b06-42c6-a52b-7a4e4d2e216c
113a6d9e-7b06-42c6-a52b-7a4e4d2e216c