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SpacesInPathNames version 4, including all changes.
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LawrenceDoliveiro |
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Unix/Linux allows any character in a file/directory name except __/__ or __[NUL]__. However, embedded spaces, newlines and the like can cause problems for carelessly-written [Shell] scripts (or scripts for [carelessly-written shells|CshProgrammingConsideredHarmful]), and cause some command [PipeLine]s to fail completely. |
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LawrenceDoliveiro |
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LawrenceDoliveiro |
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To get around this, the [GNU] versions of find(1) and xargs(1) incorporate special extensions that work together. The __-print0__ option to __find__ causes it to output matching pathnames terminated by __NUL__ characters rather than newlines, thereby avoiding confusion with any embedded newlines that might occur in the pathnames. Correspondingly, the __xargs__ command takes the option __--null__ (shorter synonym __-0__) to indicate that its input is delimited in this way; though on my [SUSE] system I also have to specify __--max-lines=1__ (shorter synonym __-L1__). |
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LawrenceDoliveiro |
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For instance, suppose I have the following files: |
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<pre> |
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Events/Weddings/Freda's Wedding/data.txt |
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Events/Car Race/data.txt |
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Events/New Year Fireworks/data.txt |
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</pre> |
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and I want to count up the number of lines in each "data.txt" file. I can do this as follows: |
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<pre> |
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find Events -name data.txt -print0 | xargs -0 -L1 wc -l |
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</pre> |
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JohnMcPherson |
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---- |
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As discussed on the BashNotes page, scripts can cope with arguments that contain spaces if you are careful. <tt>bash</tt> will expand *$@* as all of its arguments, but importantly will expand *"$@"* as each argument surrounded by "quote marks". Eg, if a script is called with arguments |
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<verbatim> |
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./myscript "argument 1" "argument 2" |
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</verbatim> |
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then a script that did |
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<verbatim> |
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perl -e 'foreach $a (@ARGV) {print ".$a.\n"}' $@ |
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</verbatim> |
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would output |
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<verbatim> |
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.argument. |
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.1. |
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.argument. |
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.2. |
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</verbatim> |
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while a script that did |
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<verbatim> |
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perl -e 'foreach $a (@ARGV) {print ".$a.\n"}' "$@" |
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</verbatim> |
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would output |
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<verbatim> |
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.argument 1. |
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.argument 2. |
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</verbatim> |
