Searching a file for keywords?

[Steve Starr]

I am trying to find out how to search a file and find certain key words
then print them.

Example:

#!/usr/bin/ruby

system("cat /proc/partitions > drives.txt")


Output:
8 0 1007616 sda
8 1 1007600 sda1
3 0 33027622 hda
3 1 14651248 hda1
3 2 14651280 hda2
3 3 3719047 hda3

Now i would just want to print the word hda to the screen.

Any help would be nice.
Thanks

 

[Robert Klemme]

I am trying to find out how to search a file and find certain key
words then print them.

Example:

#!/usr/bin/ruby

system("cat /proc/partitions > drives.txt")


Output:
8 0 1007616 sda
8 1 1007600 sda1
3 0 33027622 hda
3 1 14651248 hda1
3 2 14651280 hda2
3 3 3719047 hda3

Now i would just want to print the word hda to the screen.

Any help would be nice.
Thanks

ruby -ne 'puts "hda" if /hda/' /proc/partitions

Or, if you just want to match the exact string

ruby -ne 'puts "hda" if /\bhda\b/' /proc/partitions

And if you want to print it once only

ruby -ne '$f ||= /hda/; END { puts "hda" if $f }' /proc/partitions

From within a script

ARGF.select {|l| /hda/ =~ l}.empty? or puts "hda"

HDA - err - HTH

Kind regards

robert

 

[Ross Bamford]

I am trying to find out how to search a file and find certain key words
then print them.

Example:

#!/usr/bin/ruby

system("cat /proc/partitions > drives.txt")


Output:
8 0 1007616 sda
8 1 1007600 sda1
3 0 33027622 hda
3 1 14651248 hda1
3 2 14651280 hda2
3 3 3719047 hda3

Now i would just want to print the word hda to the screen.

Any help would be nice.
Thanks

Maybe:

File.open('/proc/partitions') do |f|
f.each_line do |s|
puts s if s =~ /hda/

# Or do you mean:
# s.scan(/hda/) { |it| puts it }
# ?
end
end

Or:

File.open('/proc/partitions') do |f|
puts f.grep(/hda/)
end

Alternatively, here's a use for that wierd gets behaviour people are
talking about, and those hateful Perl-type shortcuts:

$ ruby -ne 'print if ~/hda/' /proc/partitions

(effectively same as)

$ ruby -e 'while gets; print if ~/hda/; end' /proc/partitions

(I assume you already know about the tools that are provided for this
outside Ruby).

 

[Joel VanderWerf]

File.open('/proc/partitions') do |f|
puts f.grep(/hda/)
end

irb(main):008:0> puts IO.read('/proc/partitions').grep(/hda/)
3 0 39070080 hda
3 1 18438808 hda1
3 2 4951800 hda2
3 3 1 hda3
3 5 9855846 hda5
3 6 489951 hda6
3 7 5325516 hda7

 

[Ross Bamford]

irb(main):008:0> puts IO.read('/proc/partitions').grep(/hda/)

Ah thanks, that's better.

 

[Hal Fulton]

I am trying to find out how to search a file and find certain key words
then print them.

Example:

#!/usr/bin/ruby

system("cat /proc/partitions > drives.txt")


Output:
8 0 1007616 sda
8 1 1007600 sda1
3 0 33027622 hda
3 1 14651248 hda1
3 2 14651280 hda2
3 3 3719047 hda3

Now i would just want to print the word hda to the screen.

Here's a first stab at it:

str = `whatever_command`
arr = str.split(" ")
puts arr.grep(/hda[^0-9]/)

Assuming you just want that word and not the whole line.
Also assuming other things.


Hal

 

[Devin Mullins]

puts IO.read('/proc/partitions').grep(/hda/)

puts open('/proc/partions/){|f|f.grep /hda/}

Same number of characters, and much better memory usage for big files, I'd imagine.

Devin

 

[Joel VanderWerf]

puts open('/proc/partions/){|f|f.grep /hda/}

Same number of characters, and much better memory usage for big files,
I'd imagine.

You're quite right. Using grep on the File rather than on the string
avoids slurping the whole file at once.

(But it's not the same number of chars after you fix the typos!