In <[🔎] 20110114120047.GA7849@hysteria.proulx.com>, Bob Proulx wrote: >Adrian Levi wrote: >> zparameters="a -mhe=on -pd1ckhead -t7z -m0=lzma -mx=9 -mfb=64 -md=32m >> -ms=on -si" zfilename="Daily Backup - $(date +"%a %h %H%M >> %d-%m-%Y").$backuplevel.tar.7z" > >Yuck! Look at all of those spaces in the filename! :-) >(Recalling all of the discussion over the past couple of days >concerning whitespace in filenames and the problems that it causes.) Whitespace in filenames does not cause problems. Bad scripts (or programs) that don't pay attention to the characters allowed in their datatypes cause problems. SQL-Injection attacks have the same cause. It's single-quote and double-quote instead of whitespace, but it is the same cause. XSS attacks sometimes have the same cuase. It's a mutli-character sequence instead of whitespace, but it is the same cause. >Do you really need spaces in the filename? (Editorial remark: Unix >users always avoid putting whitespace in filenames because they are a >pain.) I use spaces in filenames all the time, but I understand the sentiment. If you don't know how your shell works it can be frustrating to deal with white space in file names. Even if you do, command-lines that deal with files whose names contain white space are a bit longer and require more hand-motion to type. >You can quote the filenames like this: > > tar $tarparameters "$backuppath" | 7z $zparameters "$zfilename" # backuppath need to be word split (it is two paths) before getting to tar tar $tarparameters $backuppath | 7z $zparameters "$zfilename" --8<-- END SCRIPT --8<-- CUT HERE -- 8<-- In general, a variable will either have contents that are mean to be word split by the shell, in which case it should be used without surrounding double-quotes but cannot be used for passing arguments containing IFS to commands OR have contents that are NOT mean to be word split by the shell, in which case it should be used with double-quotes surrounding it each time. The environment variable IFS is used for doing word splitting. If it unset, then consecutive runs of white space are delimiters. However, it can be set to other combinations (HASH, COMMA, and AT-SIGN are common to add) and will affect how word splitting is done on not-quoted expansions. In general, you should avoid not-quoted expansions where possible, but strictly conforming to the POSIX shell command language can make this difficult. Beyond the standard, many shells can handle shell variables of array types and careful use of such types should allow all use of not-quotes expansions to be eliminated. -- Boyd Stephen Smith Jr. ,= ,-_-. =. bss@iguanasuicide.net ((_/)o o(\_)) ICQ: 514984 YM/AIM: DaTwinkDaddy `-'(. .)`-' http://iguanasuicide.net/ \_/
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