Advanced subversion usage

Rebase branch on trunk

cd /working/dir/path/to/branch

svn log --stop-on-copy | tail -4 | grep ^r | cut -d' ' -f1 | sed 's/r//'
1111

svn propget db:::dweb::trunk:last_merge_from /working/dir/path/to/branch
2222

svn merge -r 1110:2222 https://remote/path/to/trunk /working/dir/path/to/branch

# check for conflicts and test

svn commit -m'Pull from trunk'

Diff branch against trunk

svn propget db:::dweb::trunk:last_merge_from /working/dir/path/to/branch
1111

svn diff https://remote/path/to/trunk@1111 https://remote/path/to/branch

When to use "or" and when to use || (double pipe) in Perl

Use || for assigning to a variable:

$a = $b || $c

Use "or" to control program flow:

$a = $b or die 'error: $b is unexpectedly false'

Mnemonic: || is a symbol like variables and numbers are, while "or" and "die" are both english words.

(source, source)

Terminal does not wrap properly in linux

Sometimes lines don't wrap correctly in a bash terminal in linux - long lines overlap and overwrite the beginning of the line instead of continuing onto the next line.

To fix it:
shopt -s checkwinsize

To check it:
shopt  | grep checkwinsize
You should see:
checkwinsize    on

If it still isn't working, try:
reset

(source)

Create a lot of random data files on linux

# Create 10Mb random data

dd bs=1024 count=10240 < /dev/urandom > data

# Split into files of 10K each

split -a 5 -b 10240 data 'split.'