如何从文件的每一行中提取具有特殊字符的特定字符串

Question

I have a file with a jungle of strings. Few lines read as follows:

 2*H[0, 3, y]*Log[1 - z] - 2*H[2, 3, y]*Log[1 - z] +
 6*H[2, 2, 0, y] + 6*H[2, 2, 2, y] - 48*Log[-Q2] + 12*zeta2*Log[-Q2] +
 (-107 + 12*N^2*(-1 + N^2))*z^2))*(H[0, 1, 0, y] + H[0, 1, 0, z] + ...

I want to find different unique combination of

H[*,*,*] or H[*,*,*,*]

coming in each line. Therefore I have to search for string containing special characters too. Is there any way to do in shell?

Answer 1

You can use this gnu awk command with custom RS :

awk -v RS='H\\[[^]]*\\]' 'RT && !seen[RT]++{print RT}' file

H[0, 3, y]
H[2, 3, y]
H[2, 2, 0, y]
H[2, 2, 2, y]
H[0, 1, 0, y]
H[0, 1, 0, z]

Regex H\\\\[[^]]*\\\\] will set each instance of H[...] as record separator.