Replace a perticular character of all lines of a file

Shell Programming and Scripting
1

Hi all,

I am new to UNIX, so sorry if my question seem stupid to u.

well i want to replace the first character of first 30 lines of a file, only if the first character is h.

and

in anothe script i want to replace a particular string/character say hello/h of a file.Condition: It should replace all Hello/h in the first line where it is found and after that it should stop.

Thanks!

2

hey experts,

please give the solution!