91–100 of 108 posts
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I use xargs a lot for refactoring work when I cannot simply use sed, e.g. vim $(grep -lr foo | xargs) and doing what I need to do on a file by file basis. Otherwise, for renaming functions and the like, I do a lot of: find . -name foo_fn exec sed -i s/foo_fn/bar_fn/g '{}' \; I generally love abusing bash. Just today I was asked about how to rename a bunch of files, specifically containing spaces, and came up with eit…
Sorry, what do you think vim $(grep -lr foo | xargs) is doing? Assuming a missing directory after the `foo' why can't it just be vim $(grep -lr foo .) I don't see that xargs's default behaviour is adding anything. For find . -name foo_fn exec sed -i s/foo_fn/bar_fn/g '{}' \; you may find -exec's + of use. The above has the fork/execve overhead for each file found. find -name '*.[ch]' -exec sed -i 's/\ /bar/g' {} +
Thanks for the suggestion about -exec +; I will have to remember it in the future.
My #1 abuse is xargs -n1. A lot of people like writing bash for loops, I will try and avoid that as much as possible, xargs -n1 is the bash equivalent of a call to 'map' in a functional language. For instance, let's say you want to create thumbnails of a bunch of jpegs: find images -name "*.jpg" | xargs -n1 -IF echo F F | sed -e 's/.jpg$/_thumb.jpg/' | xargs -n2 echo convert -geometry 200x Additionally, it's fully pa…
Why do that when a loop is clearer, safer, and shorter? find images -name '*.jpg' | while read jpg; do convert -geometry 200x "$jpg" "$(echo "$jpg" | sed 's/.jpg$/_thumb.jpg/')"; done This version works even when there are spaces in a filename, whereas yours will break.
find images -name "*.jpg" | while read -r jpg; do
convert -geometry 200x "$jpg" "${jpg%.jpg}_thumb.jpg"
done
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Sorry, what do you think vim $(grep -lr foo | xargs) is doing? Assuming a missing directory after the `foo' why can't it just be vim $(grep -lr foo .) I don't see that xargs's default behaviour is adding anything. For find . -name foo_fn exec sed -i s/foo_fn/bar_fn/g '{}' \; you may find -exec's + of use. The above has the fork/execve overhead for each file found. find -name '*.[ch]' -exec sed -i 's/\ /bar/g' {} +
You are correct on both counts regarding the vim and grep example - I guess I just assumed I would have to have all the files on a single line before handing them off to vim. Thanks for the suggestion about -exec +; I will have to remember it in the future.
I use the "grep with color for lines plus the empty string" so frequently that I have a function for it: function highlight() { local args=( "$@" ) for (( i=0; i This is only to be used as a filter, since it mangles filenames. I'm curious, does ack support a highlight-only mode?
My #1 abuse is xargs -n1. A lot of people like writing bash for loops, I will try and avoid that as much as possible, xargs -n1 is the bash equivalent of a call to 'map' in a functional language. For instance, let's say you want to create thumbnails of a bunch of jpegs: find images -name "*.jpg" | xargs -n1 -IF echo F F | sed -e 's/.jpg$/_thumb.jpg/' | xargs -n2 echo convert -geometry 200x Additionally, it's fully pa…
Why do that when a loop is clearer, safer, and shorter? find images -name '*.jpg' | while read jpg; do convert -geometry 200x "$jpg" "$(echo "$jpg" | sed 's/.jpg$/_thumb.jpg/')"; done This version works even when there are spaces in a filename, whereas yours will break.
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Do you remap ESC to another key?
No, but for me acts like and the actual keybinding is M-. or M-_. The command you are looking for is yank-last-arg for bash and insert-last-word for zsh.
foo | echoin bar
my $args = join ' ', @ARGV;
open OUT, "|$args" or die "Can't run $args: $!\n";
while () {
print $_;
print OUT $_;
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I've sometimes heard it's "catenate" not "concatenate". Do they mean the same thing? As for cat, the utility, I'm afraid we'll never stop seeing people doing cat file|prog1|prog2 even when it makes absolutely no sense whatsoever. If it did, I might as well do cat file|cat|prog|cat|prog2|cat - I mean, why not? It "looks nicer" than prog file|prog2 or prog Programmers love their cats.
It's most definitely catenate. I understand catenate to mean chain and concatenate to be to chain together. Since "cat foo bar xyzzy" doesn't modify the files to join them in any way I don't think they're chained together. Besides, ken & Co. aren't daft. con would be short for concatenate. :-)
See: http://man.cat-v.org/unix-1st/1/cat http://man.cat-v.org/unix-6th/1/cat
I'm pretty sure based on the timeline of pipe (~1973, roughly V4) that the cat command (~1971 V1) predates pipes.
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find ./ -name '*.log' -print0 | xargs -0 rm Fixes that issue and xargs is far more efficient, it doesn't launch a new process for each line like exec does, but far more importantly, xargs is generalizable to all commands so you only have to learn it once; exec is just an ugly hack on find, you can't generalize it across all commands; xargs is much more unixy.
Wanting to remove the files was so common that some finds have it built-in. Avoids even the overhead of -exec rm {} +. find -name '*.log' -delete