GREP

grep -E "[0-24]+(:[0-59]){1,}" a.txt

grep -E "^[A-Z]" a.txt

SED

sed -E  "s/([13579])([aeiou])/\2\1/g" a.txt

sed -E "s/([0-9])([0-9])/\2\1/gi" a.txt

AWK

awk '{print s=$1 + $2 }' number

UNIX SHELL

cat scor | sort | uniq -u

files=`find ./ -maxdepth 1 -type f`
ok=0
for file in $files
  do
    IFS=$'\\n'
    ok=0
    for line in ` cat $file `
      do

      if echo  $line | grep -E -q "cat"
       then
       ok=1
       fi
      done
       if [ $ok -eq 1 ]
       then
       echo $file
       fi
   done

1. What does the “open” call do before opening a FIFO to read?

open() function typically takes two arguments: the path to the FIFO and a flag that specifies the read mode (e.g. O_RDONLY or equivalent)

this call establishes a file descriptor that represents the open FIFO.

open() function may block the calling process if the FIFO is not yet open for writing

open() call will block until another process opens the same FIFO for writing

this ensures that the reader does not start reading until there is data available to be read

once the FIFO is successfully opened for reading, the process can then proceed to read data from the FIFO

1. Cate thread-uri ati folosi pentru a proces un milion de fisiere?