sarken : faq

sarken

Remove all newlines

cat file.txt | tr -d '\n' > newfile.txt

Chop the last character of a file

head -c -1 file.txt

From line i to j of file

sed -n 'i,j p' file.txt > file.new.txt

From line m to end of file

tail +m file.txt

sed -n 'm,$p' file.txt > file.new.txt

Exec'ing a command with find

find . -name "pattern" -exec cmd {} \;

Size of a file without using ls

stat -s "%s %N" file.txt

Rename file extensions using sh and sed

ls *.mp3 | sed 's/\(.\)\.mp3/mv "\1.mp3" "\1.m4a"/' | sh

Back to back tar via ssh

tar cf - files | ssh sarken.org "(cd /home/gord/tmp; tar xf -)"

Comparing two binary files byte by byte

cmp -lb file1 file2

Adding up a text file containing numbers

cat file.txt | awk '{total+=$0}END{print total}'

Parallel processing using xargs

ls *.txt | xargs -n1 -p4 doit.sh

String splitting using awk

awk 'BEGIN{FS="\n"}; { split($1, a, "foobar="); split(a[2], b, "\""); print b[2]; }'

Almost flattening an xml file

cat foobar.xml | tr '\n' ' ' | sed "s/ \( \)\+/ /g" | sed "s/<\\/closingElementTag> /\n/g

Coin Counting in Scala

def countChange(m: Int, cs: List[Int]): Int = cs match {
  case Nil => if(m == 0) 1 else 0
  case c::rs => (0 to m/c) map (k => countChange(m-k*c,rs)) sum
}