On Saturday 16 August 2008 19:13:15 David C. Rankin wrote:

Listmates,

I cannot figure out the differences that the continuations are making in the following lines of code. It looks like bash isn't handling the continuations correctly. The block of code doesn't work, the identical one-liner does. Here is the code:

BASENAME=$(echo $(basename $1 .JPG) | sed -e 's/\"//g' \ -e 's/^\s*//' -e 's/\s*$//' \ -e 's/ /_/g' -e 's/__/_/g' \ -e 's/_-_*/-/g')

BASENAME=$(echo $(basename $1 .JPG) | sed -e 's/\"//g' -e 's/^\s*//' -e 's/\s*$//' -e 's/ /_/g' -e 's/__/_/g' -e 's/_-_*/-/g')

What say the gurus?

You want to enclose the $1 in quotes if you want it to be able to handle files with spaces in their names, other than that, both versions work fine for me Anders -- To unsubscribe, e-mail: opensuse+unsubscribe@opensuse.org For additional commands, e-mail: opensuse+help@opensuse.org

----- Original Message ----- From: "David C. Rankin" To: "suse" Sent: Saturday, August 16, 2008 1:13 PM Subject: [opensuse] BASH gurus - are continuations broken?

Listmates,

I cannot figure out the differences that the continuations are making in the following lines of code. It looks like bash isn't handling the continuations correctly. The block of code doesn't work, the identical one-liner does. Here is the code:

BASENAME=$(echo $(basename $1 .JPG) | sed -e 's/\"//g' \ -e 's/^\s*//' -e 's/\s*$//' \ -e 's/ /_/g' -e 's/__/_/g' \ -e 's/_-_*/-/g')

BASENAME=$(echo $(basename $1 .JPG) | sed -e 's/\"//g' -e 's/^\s*//' -e 's/\s*$//' -e 's/ /_/g' -e 's/__/_/g' -e 's/_-_*/-/g')

What say the gurus?

What you have works fine. But, you don't need line continuation for this. Mostly for readability & maintainability and a little more thoroughness I'd do this: A=`echo "$1" |sed ' s;.*/;; s;[\"\$\&\;\*\{\}\(\)\<\>\\];;g s;\s;_;g s;^_*;; s;_*$;; s;__*;_;g s;-_;-;g s;_-;-;g s;--*;-;g s;^-;; s;\.[Jj][Pp][Gg]$;; s;[-_]$;; '` 1 strip leading path 2 strip quotes and other shell-active characters 3 convert any kind of whitespace to _ 4 strip leading _ 5 strip trailing _ 6 collapse any number of _ to one _ 7 -_ to - 8 _- to - 9 collapse any number of - to one - 10 strip leading - No * needed, there will only ever be one or none because of line 9 11 strip trailing .jpg, case insensative 12 strip trailing - or _ After stripping the extension, a formerly embedded - or _ might now be a trailing one. By this point all - and _ and combos should have been collapsed into a single - or _, so no * sould be needed. Basename replaced by lines 1 & 11 which gets rid of spawning 2 processes. .../g doesn't always make sense. For example, there is only one instance of "from here to end of line" on any given line. Order of most of the ops above matters. That handles a lot more cases than originally. Could have been done other ways too, but starting by converting all whitespace to _ makes the subsequent commands a little simpler and shorter as long as you were going to do that eventually anyways. Line 2 strips a lot more than just quotes. Maybe more than you'd like. If you are not planning on always being very careful in your handling of these filenames, always quoting the strings every time & place they are referenced or handled, then there is not much point in stripping out the spaces & quotes if you are not also going to deal with everything else that might be active on a shell command line. ";" is far more dangerous than space. escape and other control bytes are bad too though more cosmetic than dangerous. If you want to only strip quotes then line 2 only needs to be: s;\";;g If you are always going to handle the strings with care, then you can delete line 2 altogether. Leaving in the spaces & other stuff is not evil in this case because these are files that are handled by non-techy users in environments where it's OK. They don't know or care about unix file name and shell expansion considerations and why should they? Your Aunt wants "Julia & Mark's birthday!!.jpg" and I say for that kind of thing it's better to actually allow it and keep the special rules and limitations to a minimum. You, as a unix user, of course know that simple filenames are handy sometimes, but by the same token, you, as a unix user, can also be expected to simply know they ways to deal with filenames that may contain characters that may be meaningful to your shell command line. IE, you quote them. And/or you access them only from similarly safe environments yourself where no special care is needed. (graphics programs, gui file browsers, midnight commander, etc) Most programs that weren't written in crayon can handle filenames with any characters that are allowed by the filesystem. If you have say, a backup program, that chokes on _any_ filename that the filesystem even allows to exist, then don't use that backup program. Also, just as a neat example, if you trusted your filenames not to have shell active characters in them, or if you were willing to simply strip or convert any that might be in there with a few more "A=" inserted between line 1 & 2 below, then you actually don't need sed at all. A=${1//\"/} # strip quotes A=${A//_/ } # _ to " " A=`echo ${A##*/}` # strip leading path and all extra whitespace A=${A// /_} # " " to _ A=${A//_-_/-} # _-_ to - A=${A%.JPG} # strip trailing .JPG no sed, no basename, only one spawned shell line 3 the ${A##*/} syntax strips the leading path then the echo command, or rather the shell command line parser, strips the leading and trailing whitespace and collapses all embedded whitespace. -- Brian K. White brian@aljex.com http://www.myspace.com/KEYofR +++++[>+++[>+++++>+++++++<<-]<-]>>+.>.+++++.+++++++.-.[>+<---]>++. filePro BBx Linux SCO FreeBSD #callahans Satriani Filk! -- To unsubscribe, e-mail: opensuse+unsubscribe@opensuse.org For additional commands, e-mail: opensuse+help@opensuse.org