Re: GNU sed Bug (Single Quotes in Comments Cause Errors)

[Paolo Bonzini]

> #!/bin/sh
> # ScriptBrokenBySingleQuote.sh                               2
> # Created by Jonathan Levi, M.D. on 9/5/05.                  3
> str="Hello World"   # '                                      4
> strj=${str/H/J}  && #  script works if you delete this '     5
> echo ${strj/d/ds}   #                                        6
> echo $str | sed 's/H/M/ # script works if you delete this '  7
>     s/lo/low/'        #                                      8
>
>
> drj2:jonathan jonathan$ ScriptBrokenBySingleQuote.sh
> Jello Worlds
> sed: can't read 7: No such file or directory

Have you noticed 7 is the first character after the ' ?

> However, the script works if only the ' at line 7 is deleted, while 
> the ' at line 5 is retained:

Because the comment at lines 4/5 are parsed by the shell, and run until 
the end of the input line.  The # character at line 7 is in a quoted 
string, hence it is handed to sed literally together with the commands.  
Then sed looks in the quoted string and discards the comment.

Paolo