01 alias       26 gzip        51 shutdown and reboot
 02 apt-get     27 head        52 slocate
 03 bzip2       28 history     53 sort
 04 cat         29 kill        54 SSH and SCP
 05 cd          30 last        55 su
 06 chmod       31 less        56 sudo
 07 chown       32 ln          57 tail
 08 cp          33 locate      58 tar
 09 CRON        34 ls          59 top
 10 cut         35 man         60 tr
 11 date        36 mkdir       61 type
 12 declare     37 more        62 uname
 13 df          38 mv          63 uniq
 14 diff        39 passwd      64 unrar
 15 dpkg        40 paste       65 unzip
 16 echo        41 ping        66 uptime
 17 env         42 ps          67 vi
 18 eval        43 pwd         68 wc
 19 exec        44 read        69 wget and curl
 20 exit        45 rm          70 while
 21 export      46 rmdir       71 who
 22 find        47 rsync       72 whoami
 23 free        48 screen      73 whereis
 24 gawk        49 sdiff       74 xargs
 25 grep        50 sed         75 Others: &, bg, fg and nohup