mysqldump
mysqldump -u DBUSER -p DBNAME > DBNAME.sql
[Ruby] Splat operator
expand array items into individual arguments.
>> ar
=> ["a", "b"]
>> ar.class
=> Array
>> def ar_in(*args)
>> puts args, args.length
>> end
without splat
?> ar_in(ar)
a
b
1
this is what we want
>> ar_in('a', 'b')
a
b
2
>> ar_in(*ar)
a
b
2
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[Ruby] Cut with ruby
ruby -a -ne 'puts $F[1], $F[2]'
-a will split the input into an array called $F. The above will print the second and the third item of the array (based on 0 index)
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[Ruby] Comment out every line in file
ruby -i.bak -pe '$_ = "#" + $_' *
-i.bak keeps the original file safe by making a backup
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[Ruby] Grep with Ruby
ruby -ne 'puts $_ if $_ =~ /text/' *
-n places an implicit while gets ... end block
gets(separator=$/) => string or nil
------------------------------------------------------------------------
Returns (and assigns to +$_+) the next line from the list of files
in +ARGV+ (or +$*+), or from standard input if no files are present
on the command line. Returns +nil+ at end of file. The optional
argument specifies the record separator. The separator is included
with the contents of each record. A separator of +nil+ reads the
entire contents, and a zero-length separator reads the input one
paragraph at a time, where paragraphs are divided by two
consecutive newlines. If multiple filenames are present in +ARGV+,
+gets(nil)+ will read the contents one file at a time.
ARGV << "testfile"
print while gets
_produces:_
This is line one
This is line two
This is line three
And so on...
The style of programming using +$_+ as an implicit parameter is
gradually losing favor in the Ruby community.
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[Networking] Tcpdump capture traffic on port 8773 via eth1 interface
tcpdump -i eth1 -s0 -A -v port 8773
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