Bash Shell Scripting/External Programs

Bash, as a shell, is actually a 'glue' language. It helps programs to cooperate with each other, and benefits from it. Always Search The Internet for what you want -- there are lots of command line utilities available.

Using whiptail edit

Whiptail is a program that allows shell scripts to display dialog boxes to the user for informational purposes, or to get input from the user in a friendly way. Whiptail is included by default on Debian and various other GNU/Linux distributions.

From the GNU/Linux Dictionary: whiptail is a "dialog" replacement using newt instead of ncurses.
From its README: whiptail is designed to be drop-in compatible with dialog(1), but has fewer features: some dialog boxes are not implemented, such as tailbox, timebox, calendarbox, etc.

See Bash Shell Scripting/Whiptail.

Using AWK edit

See AWK and man awk (man gawk).

Using sed edit

See sed and man sed.

Using grep edit

See grep and man grep.

Using man, info and help edit

These three programs are where you can find help or reference from. man displays roff manual pages, info displays texinfo documentations, while help displays builtin helps.

Appending --long-help, --help or --usage to a command-line program may also gives you the usage information. Possible synonyms include -H and -h.

Just try these out:

man --help
man man

info --help
man info
info info

help help

Pressing h in man and info's interfaces can also give you some direction.