ruakh

203 reputation

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	location	Seattle, WA
	age	28
visits	member for	1 year, 6 months
	seen	May 17 at 5:21
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	203 reputation	bio	website		visits	member for	1 year, 6 months
14 badges		location	Seattle, WA		seen	May 17 at 5:21

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May 16	comment	Can sed remove 'double' newline characters? For the first Perl one, you should actually set `$/` to `""` (which is a magic value for just this sort of purpose).
Feb 22	awarded	Editor
Feb 22	revised	Why is printf better than echo? avoid use of "echo" to mean specifically "a certain version of echo that is not the one found in Bash and various other shells"
Feb 22	suggested	suggested edit on Why is printf better than echo?
Feb 11	comment	Iterate over multiple parameters with spaces in bash script But what if the filenames contain newlines?
Feb 8	comment	What's a safe and portable way to split a string in shell programming? @rahmu: O.K., but be careful: `IFS` is often unset by default, which is not the same as being the empty string. When restoring it, you need to preserve that distinction.
Feb 3	comment	What's the equivalent to && when writing a bash script? @kojiro: Whoops, thanks for the correction. I see what you mean, then. :-)
Feb 3	comment	What's the equivalent to && when writing a bash script? Unfortunately, there are a number of standard utilities that don't follow the usual exit-status conventions, so `-e` can misbehave. For example, you probably don't want your script to terminate every time you `diff` two non-identical files. You can, of course, work around this by appending `\|\| true` (or perhaps `\|\| [ $? = 1 ]`) to such commands, but the OP mentions an "everyone else" who will have to read this script, and said "everyone else" will probably not be used to having to cope with `-e`.
Feb 3	comment	What's the equivalent to && when writing a bash script? @kojiro: I don't see the distinction. `a && b && c` will only run `b` if `a` succeeds, so "it only runs `c` if `b` succeeds" and "it only runs `c` if `a` and `b` both succeed" are equivalent statements: `b` can't succeed unless `a` succeeded.
Nov 28	comment	What's a good way to filter a text file to remove empty lines? @JosephR.: What happens is, `$` can match before a newline (provided that either the `/m` flag is enabled, or the newline is the very last character of the string, or both), but it can also match the end of the string. For example, `"abc" =~ m/^abc$/` is true. In the case of `\s$`, the `\s` is greedy enough to eat up the newline, and then the `$` matches the end-of-string. (But I think `s/^\s*\n//` is clearer, anyway, so your answer is just fine as it is now.)
Nov 28	comment	What's a good way to filter a text file to remove empty lines? @JosephR.: The `\n` itself can be removed; what you can't do is remove both the `$` and the `\n`. So `s/^\s//` would have the problem you describe, but `s/^\s$//` would be fine, because of the `\s*` and the `$`. (Do you see what I mean?)
Nov 28	comment	What's a good way to filter a text file to remove empty lines? You don't need the `$`, given that you have the `\n`. (Alternatively -- you don't need the `\n`, given that you have the `\s` and the `$`; but I think `s/^\s\n//` makes it clearer that the newline is removed.) You also don't need the `/m`; it has no effect on this command. And once you get rid of the `$` and the space, you won't need the `/x`.
Nov 13	awarded	Yearling
Oct 27	comment	Why does --text=“$@” only pass the first word? @jw013: See manatwork's comment above. His first quote, `Word splitting is not performed, with the exception of "$@"`, comes from the explanation of the processing of the right-hand-side of variable assignments. (Just search gnu.org/software/bash/manual/bash.html for that string.)
Oct 27	comment	Why does --text=“$@” only pass the first word? @jw013: But according to the Bash Reference Manual, `"$@"` does undergo word splitting, even in variable assignments.
Oct 24	comment	Delete last line from the file @Rob: `sed '$d' file` doesn't actually modify the file; it just prints out the contents of the file, minus the last line. So `sed '$d' file; sed '$d' file` will print out the contents of the file twice, minus the last line each time. The delete-the-last-two-lines equivalent of `sed '$d' file` is `sed '$d' file \| sed '$d'`.
Oct 5	awarded	Commentator
Oct 5	comment	Why can't I redirect a path name output from one command to “cd”? Different shells, yes; but different "systems"? Are there really any shells that will support `$(...)` on one system but not on another??
Oct 5	comment	Why can't I redirect a path name output from one command to “cd”? The OP already stated, in his/her question, that `$(...)` works. I don't think it's good advice to recommend backticks instead, since they have much more convoluted quoting rules and are generally more error-prone. (See §3.5.4 "Command Substitution" in the Bash Reference Manual.)
Sep 21	comment	How to match case insensitive patterns with ls? @mtk: To set an option, you use `shopt -s`; to unset it, you use `shopt -u`. Alternatively, you can wrap everything in a subshell by using `( )` so that the setting doesn't affect the parent shell: `(shopt -s nocaseglob ; ls abc)`.