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Select with long list

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.

Comments

  • marcmarc Posts: 647
    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
  • atreyuatreyu Posts: 216
    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
  • dwclarkedwclarke Posts: 12
    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
    
  • Goineasy9Goineasy9 Posts: 1,116
    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.
  • marcmarc Posts: 647
    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
  • dwclarkedwclarke Posts: 12
    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 &#91;&#91; ! $answer = *[!0-9]* &#91;&#91;
    

    Of course, much simpler, although, should that be '==' not '='?. While Googling, I also found the similar
     if &#91;&#91; $answer =~ ^[0-9]+$ &#91;&#91;;
    

    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.
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