[duneomvs]

Hello,
I am having a problem using sed to substitute hex data in a file. I have no problem with using sed for simple substitution ie (sed s’/a/b/g’ file a > file b) (replace all a’s in file a with b’s). What I need to do is something like this (sed s’/\x20/\x30/g’ file a > file b) (where \x20 is the hex for ‘ ‘ and \x30 is the hex for ‘0’). Does anyone know the proper syntax for this?

Thanks.

[Tesseract]

sed isn't really designed for working with binary data. You might have better luck with tr, which accepts the \xxx octal escapes (and maybe other types as well - check its man page).

Be sure to single-quote all your arguments so the shell doesn't eat the backslashes. You may wish to try your arguments with echo first if you aren't sure what's going on.

[whgoodman]

You can get the list of octal, hex and decimal codes for use in the tr command by issuing a 'man ascii' in the CLI.

Walt

[duneomvs]

Thanks Guys,

tr worked great.

[Hal Itosis]

Originally Posted by duneomvs

I am having a problem using sed to substitute hex data in a file. I have no problem with using sed for simple substitution ie (sed s’/a/b/g’ file a > file b) (replace all a’s in file a with b’s). What I need to do is something like this (sed s’/\x20/\x30/g’ file a > file b) (where \x20 is the hex for ‘ ‘ and \x30 is the hex for ‘0’). Does anyone know the proper syntax for this?

While the answers above apply well to 'binary' data
if instead you were referring to text inside of a text file...
then all that was needed was to "escape the escape."
Sorta like this...

Code:
hostname:~ (501) $ echo \x20
x20
hostname:~ (502) $ echo \\x20 
\x20
hostname:~ (503) $ echo '\x20'
\x20
hostname:~ (504) $ echo '\x20' | sed 's/\\x20/\\x30/g'
\x30
hostname:~ (505) $

Maybe without slashes it's easier to see:
sed 's:\\x20:\\x30:g'