Welcome to the Linux Foundation Forum!
Select with long list
dwclarke
Posts: 12
in Command Line
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.
0
Comments
-
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
Regards0 -
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.#!/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 $answer
just replace the vars= line with your 150 variables. btw, i used more instead of less - personal pref.
-bill0 -
Thanks for that. I've moded it a bit, and have ended up with this:
#!/bin/bash # Script for a user to select a file echo "Remember the number of the file you want, then press 'q', and enter the number" echo "Press any key to start" # Wait for keypress read -n 1 -s # Show numerated file list ls *.txt | cat -n | less #Get users file selection number until [ -n "$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
0 -
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.0
-
If I may add some suggestions:
# Show numerated file list ls *.txt | cat -n | less
Yo do not need to pipe anything here, just doless -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 testif [[ ! $answer = *[!0-9]* [[
# check the number isn't bigger than the list of files count=`ls *.txt | wc -l`
Don't ever parse the output of ls!!!. Insted:f=(*.txt) count=${#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 [ [
Regards0 -
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 doless -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 testif [[ ! $answer = *[!0-9]* [[
Of course, much simpler, although, should that be '==' not '='?. While Googling, I also found the similarif [[ $answer =~ ^[0-9]+$ [[;
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?
YupYou 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.0
Categories
- 8.8K All Categories
- 13 LFX Mentorship
- 66 LFX Mentorship: Linux Kernel
- 355 Linux Foundation Boot Camps
- 228 Cloud Engineer Boot Camp
- 67 Advanced Cloud Engineer Boot Camp
- 23 DevOps Engineer Boot Camp
- 4 Cloud Native Developer Boot Camp
- 738 Training Courses
- 14 LFC110 Class Forum
- 16 LFD102 Class Forum
- 96 LFD103 Class Forum
- 2 LFD121 Class Forum
- 55 LFD201 Class Forum
- 1 LFD213 Class Forum - Discontinued
- 128 LFD232 Class Forum
- 14 LFD254 Class Forum
- 425 LFD259 Class Forum
- 78 LFD272 Class Forum
- 1 LFD272-JP クラス フォーラム
- 15 LFS200 Class Forum
- 686 LFS201 Class Forum
- LFS201-JP クラス フォーラム
- 271 LFS211 Class Forum
- 50 LFS216 Class Forum
- 23 LFS241 Class Forum
- 26 LFS242 Class Forum
- 18 LFS243 Class Forum
- 4 LFS244 Class Forum
- 7 LFS250 Class Forum
- LFS250-JP クラス フォーラム
- 105 LFS253 Class Forum
- 754 LFS258 Class Forum
- 7 LFS258-JP クラス フォーラム
- 48 LFS260 Class Forum
- 75 LFS261 Class Forum
- 6 LFS262 Class Forum
- 76 LFS263 Class Forum
- 14 LFS264 Class Forum
- 10 LFS266 Class Forum
- 8 LFS267 Class Forum
- 8 LFS268 Class Forum
- 5 LFS269 Class Forum
- 173 LFS272 Class Forum
- 1 LFS272-JP クラス フォーラム
- 184 LFW211 Class Forum
- 100 LFW212 Class Forum
- 876 Hardware
- 205 Drivers
- 74 I/O Devices
- 43 Monitors
- 115 Multimedia
- 204 Networking
- 98 Printers & Scanners
- 82 Storage
- 716 Linux Distributions
- 78 Debian
- 64 Fedora
- 12 Linux Mint
- 13 Mageia
- 22 openSUSE
- 125 Red Hat Enterprise
- 33 Slackware
- 13 SUSE Enterprise
- 344 Ubuntu
- 445 Linux System Administration
- 33 Cloud Computing
- 63 Command Line/Scripting
- Github systems admin projects
- 88 Linux Security
- 73 Network Management
- 105 System Management
- 45 Web Management
- 50 Mobile Computing
- 18 Android
- 19 Development
- 1.2K New to Linux
- 1.1K Getting Started with Linux
- 499 Off Topic
- 119 Introductions
- 193 Small Talk
- 19 Study Material
- 743 Programming and Development
- 237 Kernel Development
- 472 Software Development
- 899 Software
- 245 Applications
- 178 Command Line
- 2 Compiling/Installing
- 72 Games
- 313 Installation
- 19 All In Program
- 19 All In Forum
Upcoming Training
-
August 20, 2018
Kubernetes Administration (LFS458)
-
August 20, 2018
Linux System Administration (LFS301)
-
August 27, 2018
Open Source Virtualization (LFS462)
-
August 27, 2018
Linux Kernel Debugging and Security (LFD440)