$ history
    1  ifco
    2  /sbin/ifconfig
    3  nmap
    4  time > /dev/null
    5  time 2> /dev/null
    6  time ls /dev/null
    7  time ls > /dev/null
    8  time ls 2> /dev/null
    9  time ls >/dev/null  2>&1
   10  strace time ls >/dev/null  2>&1
   11  strace time ls >/dev/null
   12  type time
   13  which time
   14  bash -c "time ls" >/dev/null
   15  bash -c "time ls" 2>/dev/null
   16  ifco
   17  /sbin/ifconfig
   18  ping 10.96.16.9
   19  ssh 10.96.16.9
   20  ssh 127.0.0.1
   21  sudo useradd -m remote
   22  sudo passwd remote
   23  ssh 127.0.0.1
   24  ssh remote@127.0.0.1
   25  man mknod
   26  cat fifo
   27  dmesg
   28  sudo dmesg
   29  ls /dev/sdc
   30  df -h
   31  mkdir os-20.11
   32  ls
   33  A=$(ls)
   34  echo $A
   35  man bash
   36  env LANG
   37  echo $LANG
   38  export LANG=ru_RU.utf8
   39  asd
   40  export LANG=en_US.utf8
   41  asd
   42  LANG=en_US.utf8
   43  asd
   44  date
   45  cd os-20.11/
   46  vim 5min.txt
   47  ps aux | grep cron
   48  cat
   49  grep
   50  which passwd
   51  ls -la /usr/bin/pas
   52  ls -la /usr/bin/passwd
   53  [ $A > 2 ]
   54  [ $A > 2 ] && echo OK
   55  [ "$A" > 2 ] && echo OK
   56  [ "$A" > 2 & "$B" < 3 ] && echo OK
   57  [[ "$A" > 2 & "$B" < 3 ]] && echo OK
   58  [[ "$A" > 2 && "$B" < 3 ]] && echo OK
   59  [ "$A" > 2 && "$B" < 3 ] && echo OK
   60  man test
   61  ls /dev/
   62  ls -l /dev/
   63  # MAJOR MINOR
   64  ls -l /dev/ | head
   65  ls -l /dev/random
   66  ls -l /dev/urandom
   67  man mknod
   68  mknod foobar 1 9
   69  mknod foobar c 1 9
   70  sudo mknod foobar c 1 9
   71  ls -l
   72  hd foobar
   73  hexdump /bin/ls
   74  hd /bin/ls
   75  ls -l
   76  # FIFO = First In First Out
   77  ls | sort
   78  mknod fifo p
   79  ls -l
   80  echo hello > fifo
   81  mkfifo fifo2
   82  ls -l
   83  # chmod
   84  ls -l
   85  sudo chown user foobar
   86  ls -l foobar
   87  sudo chown user:user foobar
   88  ls -l foobar
   89  df
   90  df -h
   91  mkdir flash
   92  sudo mount /dev/sdc flash
   93  ls flash/
   94  sudo umount flash/
   95  ls flash/
   96  sudo mount /bin/ls flash
   97  dmesg | tail
   98  sudo dmesg | tail
   99  sudo mount /dev/sdc flash
  100  df -h
  101  sudo umount flash/
  102  dmesg
  103  sudo dmesg
  104  cat /etc/fstab
  105  du .
  106  du -sch .
  107  du -sch /etc
  108  sudo du -sch /etc
  109  sudo du -sc /etc
  110  sudo du -s /etc
  111  sudo du /etc
  112  sudo du -s /etc
  113  sudo du -c /etc
  114  man du
  115  man stat
  116  ls -lh 5min.txt
  117  stat 5min.txt
  118  hd 5min.txt
  119  man dd
  120  mount
  121  mount /
  122  mount
  123  dd if=/dev/sda of=sector0.bin bs=1024 count=1
  124  sudo dd if=/dev/sda of=sector0.bin bs=1024 count=1
  125  ls -l
  126  hd sector0.bin
  127  hd -v sector0.bin
  128  sudo dd if=/dev/sda of=sector3.bin bs=512 count=1 skip=3
  129  ls -l
  130  ls /boot/
  131  ls /boot/ -la
  132  bc
  133  bc "2^1000"
  134  man bc
  135  echo "2^10" | bc
  136  echo 2+2 > bc
  137  bc < bc
  138  reboot
  139  poweroff
  140  sudo reboot
  141  bmon
  142  cd os-20.11/
  143  vim test.txt
  144  nano awk.txt
  145  chmod +x awk.txt
  146  ./awk.txt test.txt
  147  nano awk.txt
  148  ./awk.txt test.txt
  149  nano awk.txt
  150  less awk.txt
  151  ls
  152  rm fifo fifo2 foobar
  153  ls -la
  154  rmdir flash/
  155  history

$ for i in *; do echo === $i ===; cat $i; done
=== 100.txt ===
1
2
3
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100
=== 2 ===
=== 5min.txt ===
1. Каким рег.выром выбрать 10 подряд идущих символов "a"?
   (не так: aaaaaaaaaa)

   a{10}

2. Какой символ в рег.выре соответствует любому символу
   строки?

   .

3. Как сопоставить строку с рег.выром в bash?
   (2 способа)

   [[ "$A" =~ a{10} ]]
   grep -P "a{10}"

4. Как объявить массив в bash?

   declare -a A

5. Как найти все подкаталоги в /etc при помощи find?

   find /etc -type d
=== awk.txt ===
#!/usr/bin/awk -f
BEGIN {
	for (i=0; i<10; i++) {
		print "i=" i
	}
}

/1/    { sum1    += $2 }
       { sum_all += $2 }
$1 > 2 { sum2    += $2 }

END    {
	print sum1
	print sum_all
	print sum2
}
=== bc ===
2+2
=== test.txt ===
1	100
2	200
3	300
4	400
5	500