$#,

$((expression)),

$*,

$0,

$@,

${!array[*]},

${!array[@]},

${!prefix*},

${!prefix@},

${#parameter},

${parameter##pattern},

${parameter#pattern},

${parameter%%pattern},

${parameter%pattern},

${parameter/#pattern/string},

${parameter/%pattern/string},

${parameter//pattern/string},

${parameter/pattern/string},

${parameter:+word},

${parameter:-word},

${parameter:=word},

${parameter:?word},

(( )) compound command, ,

--help option,

./configure,

.bashrc, , , , ,

.bash_history,

.bash_login,

.bash_profile,

.profile,

.ssh/known_hosts,

/,

/bin,

/boot,

/boot/grub/grub.conf,

/boot/vmlinuz,

/dev,

/dev/cdrom,

/dev/dvd,

/dev/floppy,

/dev/null,

/etc,

/etc/bash.bashrc,

/etc/crontab,

/etc/fstab, , ,

/etc/group,

/etc/passwd, , , , ,

/etc/profile, ,

/etc/shadow,

/etc/sudoers,

/lib,

/lost+found,

/media,

/mnt,

/opt,

/proc,

/root, ,

/sbin,

/tmp, ,

/usr,

/usr/bin,

/usr/lib,

/usr/local,

/usr/local/bin, ,

/usr/local/sbin,

/usr/sbin,

/usr/share,

/usr/share/dict,

/usr/share/doc, ,

/var,

/var/log,

/var/log/messages, , ,

[ command,

“hello world” program,

“release early, release often,” 369,