# Bash manual page selection menu

I wrote the following script in the hopes of streamlining the finding and reading of multiple manual pages. Since I am always looking up different utilities' manual pages I thought this would a good learning aid.

#!/bin/bash

while true
do
echo
echo "1) /bin"
echo "2) /sbin"
echo "3) /usr/bin/"
echo "4) /usr/sbin"
echo "5) /usr/local/bin"
echo "6) /usr/local/lib"
echo "7) /usr/local/share"
echo "8) /usr/local/include"
echo "9) exit"
echo
read -p 'Select a directory ' d
if [[ $d = 1 ]]; then dir=/bin elif [[$d = 2 ]]; then
dir=/sbin
elif [[ $d = 3 ]]; then dir=/usr/bin elif [[$d = 4 ]]; then
dir=/usr/sbin
elif [[ $d = 5 ]]; then dir=/usr/local/bin elif [[$d = 6 ]]; then
dir=/usr/local/lib
elif [[ $d = 7 ]]; then dir=/usr/local/share elif [[$d = 8 ]]; then
dir=/usr/local/include
elif [[ $d = 9 ]]; then exit else echo 'No such directory' exit 1 fi echo while true do menu=($(ls -1 ${dir}) ) i=0 for m in${menu[@]}
do
echo "$(( i++ )))$(basename $m)" done | xargs -L3 | column -t echo echo 'Select from the list above' echo 'Type b to go back to main menu' read -p 'Type q to quit at anytime ' n echo if [[$n = 'b' || $n = 'B' ]]; then break 1 elif [[$n = 'q' || $n = 'Q' ]]; then exit else for item in${menu[$n]} do if [[$item =~ '.txt' ]]; then
item="$(echo${item%.*})"
fi
man $item done fi done done  One thing I should point out. My /usr/local/bin directory has several .txt files. That is the reason for if [[$item =~ '.txt' ]]; then item="$(echo${item%.*})"; fi Maybe it is normal to have plain text files in this directory or maybe this is something I did unintentionally when experimenting writing this script. (An earlier version of this script wrote all the man pages to plain text files.) I really don't know but that's why that part of the script is there.

I think this script does what I hoped it would do so now I would like other people's opinion. Is there anything I could do better? Am I overlooking anything?

### Use a table driven menu

The menu to select from /bin, /sbin and other is very repetitive. A table-based approach would be more compact, easier to write and maintain. Try to use an array, as you did in other places of the script.

First, put the directories in an array, for example:

dirs=('' /bin /sbin /usr/bin)  # fill the rest


Note that I added a dummy empty first element. This is to make the 1-based indexes of your menu work with the 0-based array indexes.

Build the menu from this array using a counting loop from 1, the first non-empty element:

for ((index = 1; index < ${#dirs[@]}; index++)); do echo "$index) ${dirs[$index]}"
done


To validate the user input, simply check if ${dirs[$index]} is empty. If yes, the input is invalid.

### Security

Maybe it is normal to have plain text files in this directory or maybe this is something I did unintentionally when experimenting writing this script. (An earlier version of this script wrote all the man pages to plain text files.)

No, it is not normal to have .txt files in any of those directories. So I guess your earlier script put them there. But a normal user should not have write access to these directories. Which seems to suggest that you're playing with a privileged account, possibly root. That's a bad idea, avoid using root casually.

You can simplify [[ $n = 'b' ||$n = 'B' ]] using pattern matching: [[ $n == [bB] ]]. ### Strangeness You don't need the -1 here. menu=($(ls -1 ${dir}) )  When inside $(...), ls does not columnize its output.

In this code, I don't see why you need basename:

echo "$(( i++ )))$(basename $m)"  It seems the value of $m will always be a simple filename without a path part.

• Thank you I have put the directories into an array as you suggested. But I don't understand what you mean by "To validate the user input, subtract 1 to offset the +1 we printed for display purposes, and then check if ${dirs[$index]} is empty. If yes, the input is invalid" Could you explain this a little more? – I0_ol Sep 19 '16 at 22:50
• What I meant was, be careful that array indexes are 0-based, but your menu options are 1-based. So when displaying the menu, we show array index+ 1, and when parsing user input, we must do the reverse and apply -1 to convert user input to array index. Actually there's a simpler way, I now realize: make the first array element an empty dummy element. That way you can display the menu starting from index 1, and then the user input must directly correspond to array indexes, no more math is necessary – janos Sep 20 '16 at 5:12
• I updated my answer with this latest idea to simplify the index manipulations – janos Sep 21 '16 at 5:37
• Way late to the party, but \$dir/* and select would be nicer than ls and a hand-built menu. – D. Ben Knoble Jun 4 at 3:18