fgrep

fgrepは、grep -Fと同じ。パターン文字列をただの文字列として扱う
-F, --fixed-strings, --fixed-regexp Interpret PATTERN as a list of fixed strings, separated by newlines, any of which is to be matched. (-F is specified by POSIX, --fixed-regexp is an obsoleted alias, please do not use it in new scripts.)

[linuxstudy@xxxx ~]$ cat find.txt 
abcdef
abc[^a]ef
[linuxstudy@xxxx ~]$ fgrep abc[^a]ef find.txt  //abc[^a]efという文字列を検索
abc[^a]ef
[linuxstudy@xxxx ~]$ grep abc[^a]ef find.txt   //正規表現abc[^a]efを検索
abcdef