Select with long list

dwclarke

I'm writing a command line script, where I want the user to select a file name. The select command almost does the job, but the list of files is rather long, about 150.

Anyone know of a way of throwing something like less into the mix, to enable the user to scroll around the list before selecting?

Cheers.

marc

dwclarke wrote:

I'm writing a command line script, where I want the user to select a file name. The select command almost does the job, but the list of files is rather long, about 150.

Anyone know of a way of throwing something like less into the mix, to enable the user to scroll around the list before selecting?

Cheers.

Select is rather strict and unflexible. You can relay on the usual buffer of any terminal (scrolling with SHIFT+PgUp/PgDown ).

You are better off writting your own menu though

Regards

atreyu

dwclarke wrote:

I'm writing a command line script, where I want the user to select a file name. The select command almost does the job, but the list of files is rather long, about 150.

Anyone know of a way of throwing something like less into the mix, to enable the user to scroll around the list before selecting?

Cheers.

I've never used select before, but I do use Bash's builtin read function, in conjunction with a loop, to do this very thing. something like this might work:

#!/bin/bash
listfiles(){
  vars=`seq 1 150`
  for var in $vars; do
    echo $var
  done
}
listfiles|more
until [ -n "$answer" ]; do
  echo -n "Enter your selection: "
  read answer
done
echo you selected $answer

just replace the vars= line with your 150 variables. btw, i used more instead of less - personal pref.

-bill

dwclarke

Thanks for that. I've moded it a bit, and have ended up with this:

#!/bin/bash 
# Script for a user to select a file
 
echo "Remember the number of the file you want, then press 'q', and enter the number"
echo "Press any key to start"

# Wait for keypress
read -n 1 -s 

# Show numerated file list
ls *.txt | cat -n | less

#Get users file selection number
until [ -n "$answer" ]; do 
  echo -n "Enter your selection: " 
  read answer 
done

# Check entry is numeric
if echo $answer | grep "^[0-9]*$" > /dev/null
then

 # check the number isn't bigger than the list of files
 count=`ls *.txt | wc -l`
 if [ $answer -le $count ]
 then

   ourfile=`ls *.txt | sed -n "$answer p"`
   echo "You chose $ourfile"

 else
  echo "Number is too large"
 fi

else
 echo "$answer is not numeric"
fi

Goineasy9

I think I learn more from this sub-forum than any of the others. Thanks to all that post code here. As someone who never had to write bash code, I like watching others discuss it.

marc

If I may add some suggestions:

# Show numerated file list
ls *.txt | cat -n | less

Yo do not need to pipe anything here, just do

less -N *.txt

# Check entry is numeric
if echo $answer | grep "^[0-9]*$" > /dev/null

Again, you do not need to pipe anything. This checks if it contains non numeric characters: a2 or 34s will fail the test

if [[ ! $answer = *[!0-9]* [[

 # check the number isn't bigger than the list of files
 count=`ls *.txt | wc -l`

Don't ever parse the output of ls!!!. Insted:

f=(*.txt)
count=${#f[@]}

WARNING: this does not check if there are no .txt files <--- it will fail in that case as it will return a one file (the * glob)

   ourfile=`ls *.txt | sed -n "$answer p"`
   echo "You chose $ourfile"

I'm not quite sure what's your intention here...

I'm assuming you are using bash, aren't you?

You should avoid `command` as it is deprecated and not easy to nest (try nesting 3-4 things and you'll understand what I mean). Try $(command) instead

If you are using bash.... you should use [ [ instead of [ . The [ command (yes, it is a command, not a built in shell option) is, by far, less powerfull than the built in [ [

Regards

dwclarke

Thanks for your substantial suggestions, it's been very educational. I'll go through the bits:

marc wrote:

If I may add some suggestions:

# Show numerated file list
ls *.txt | cat -n | less

Yo do not need to pipe anything here, just do

less -N *.txt

Your suggestion gave me the contents of the files, whereas I need to search through the file names, to pick one. I did use the -N for less, though, to give me:

# Show numerated file list
ls *.txt | less -N

# Check entry is numeric
if echo $answer | grep "^[0-9]*$" > /dev/null

Again, you do not need to pipe anything. This checks if it contains non numeric characters: a2 or 34s will fail the test

if [[ ! $answer = *[!0-9]* [[

Of course, much simpler, although, should that be '==' not '='?. While Googling, I also found the similar

 if [[ $answer =~ ^[0-9]+$ [[;

Which gets rid of the double negation.

 # check the number isn't bigger than the list of files
 count=`ls *.txt | wc -l`

Don't ever parse the output of ls!!!. Insted:

f=(*.txt)
count=${#f[@]}

That works for me, although I'm interested as to why the output of ls shouldn't be used for parsing (besides being unnecessary)

WARNING: this does not check if there are no .txt files <--- it will fail in that case as it will return a one file (the * glob)

Luckily I do this earlier, in an unshown part of the code.

   ourfile=`ls *.txt | sed -n "$answer p"`
   echo "You chose $ourfile"

I'm not quite sure what's your intention here...

This takes the number, and converts it into the filename we've picked. With what you've just taught me, I should be able to simplify this.

I'm assuming you are using bash, aren't you?

Yup

You should avoid `command` as it is deprecated and not easy to nest (try nesting 3-4 things and you'll understand what I mean). Try $(command) instead
[\quote]

I didn't know that. I've been using the Bash Beginners Guide and Advanced Bash Scripting Guide for my main references.

If you are using bash.... you should use [ [ instead of [ . The [ command (yes, it is a command, not a built in shell option) is, by far, less powerfull than the built in [ [
[\quote]

Thanks for that, I've spent a very instructive afternoon re-writing my code.

As an aside, anyone copying the code, it is missing the code Exit's, when an error is found.