Comments on: Useless use of … http://glandium.org/blog/?p=220 glandium.org Sun, 05 Sep 2010 12:27:46 +0000 hourly 1 http://wordpress.org/?v=3.0.1 By: Denilson http://glandium.org/blog/?p=220&cpage=1#comment-11784 Denilson Mon, 05 Jan 2009 19:29:12 +0000 http://glandium.org/blog/?p=220#comment-11784 Talking about "wc"... If you want to know the size of a file in bytes, "wc -c foo.bar" is the best choice, because it will be smart enough to not read the whole file, but instead will seek directly to the end, or get the size from file stats. In other words, "wc -c" is fast, while "wc" isn't. Other option is "find -printf '%s %p\n'" Talking about “wc”…

If you want to know the size of a file in bytes, “wc -c foo.bar” is the best choice, because it will be smart enough to not read the whole file, but instead will seek directly to the end, or get the size from file stats. In other words, “wc -c” is fast, while “wc” isn’t.

Other option is “find -printf ‘%s %p\n’”

]]> By: ushimitsudoki http://glandium.org/blog/?p=220&cpage=1#comment-11753 ushimitsudoki Sun, 21 Dec 2008 16:01:46 +0000 http://glandium.org/blog/?p=220#comment-11753 Wow! I am guilty of some of these. Please keep this series up! Wow! I am guilty of some of these.

Please keep this series up!

]]> By: glandium http://glandium.org/blog/?p=220&cpage=1#comment-11751 glandium Sun, 21 Dec 2008 12:09:58 +0000 http://glandium.org/blog/?p=220#comment-11751 Julian: Actually, the less-than symbol was supposed to be in my post, but somehow didn't get there. Seems like the comment system also has problems. Julian: Actually, the less-than symbol was supposed to be in my post, but somehow didn’t get there. Seems like the comment system also has problems.

]]> By: Julian Andres Klode http://glandium.org/blog/?p=220&cpage=1#comment-11749 Julian Andres Klode Sun, 21 Dec 2008 00:36:05 +0000 http://glandium.org/blog/?p=220#comment-11749 Your Blog has problems with the less-than symbol in comments. It just ignores everything after it. Your Blog has problems with the less-than symbol in comments. It just ignores everything after it.

]]> By: Julian Andres Klode http://glandium.org/blog/?p=220&cpage=1#comment-11748 Julian Andres Klode Sun, 21 Dec 2008 00:34:17 +0000 http://glandium.org/blog/?p=220#comment-11748 more $file | wc | awk '{print $1}' is not the same as wc -l $file, it is the same as "wc -l < $file" more $file | wc | awk ‘{print $1}’ is not the same as wc -l $file, it is the same as “wc -l < $file”

]]> By: Tzafrir Cohen http://glandium.org/blog/?p=220&cpage=1#comment-11747 Tzafrir Cohen Sat, 20 Dec 2008 16:25:41 +0000 http://glandium.org/blog/?p=220#comment-11747 actually wc is one of them. Hence the two commands you mentioned are not exactly the same: $ wc -l test_doc 0 test_doc $ wc -l < test_doc 0 actually wc is one of them. Hence the two commands you mentioned are not exactly the same:

$ wc -l test_doc
0 test_doc
$ wc -l < test_doc
0

]]> By: Simon http://glandium.org/blog/?p=220&cpage=1#comment-11746 Simon Sat, 20 Dec 2008 13:50:33 +0000 http://glandium.org/blog/?p=220#comment-11746 The other reason you might want the "cat file |" bit is that this way, stdin is a pipe rather than a file. Some programs behave differently when stdin is not seekable. The other reason you might want the “cat file |” bit is that this way, stdin is a pipe rather than a file. Some programs behave differently when stdin is not seekable.

]]> By: Jon http://glandium.org/blog/?p=220&cpage=1#comment-11745 Jon Sat, 20 Dec 2008 11:49:52 +0000 http://glandium.org/blog/?p=220#comment-11745 cat file | pipe-construction is not always totally useless. When iteratively building a piped set of commands, you may do something like head some-file | try-some-stuff to ensure you've matched on the right columns, etc.; then when you are happy it works you do something like ^head^cat; or even manually edit the line and insert cat at the front, which may be quicker than reworking the line to avoid the 'useless' invocation. cat file | pipe-construction is not always totally useless. When iteratively building a piped set of commands, you may do something like head some-file | try-some-stuff to ensure you’ve matched on the right columns, etc.; then when you are happy it works you do something like ^head^cat; or even manually edit the line and insert cat at the front, which may be quicker than reworking the line to avoid the ‘useless’ invocation.

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