BASH Scripting

[Matthew S-H]

I hope I'm not becoming a bother.  If I am, just let me know and I'll  
find another list to post my BASH questions on.

Anyway, I am still having a little trouble scripting.  I don't quite  
understand tests (when to use == or -eq, for example).

If any of you could look at my code, I'd appreciate it.

> #!/bin/bash
>
> #************************************************#
> #                 file_prompt.sh                 #
> #        written by Matthew Strax-Haber          #
> #             Started June 19, 2005              #
> #          Last Modified June 26, 2005           #
> #                                                #
> #         Lists files in a dir and asks          #
> #            the user which to select            #
> #************************************************#
>
> E_FILE_DOES_NOT_EXIST=85
> E_PERM_DENIED=87
> E_FILE_NOT_DIR=88
> E_NEED_ARGS=95
> E_INVALID_USER_INPUT=98
> work_dir=$1                     # directory to work in
> prompt=${2-"Choose"}            # prompt to show user
> full_pathQQQ=$3                 # whether output should be full path
> #chosen_num                     # Num from prompt
> #chosen_file                    # Name of chosen file
> max_tries=3                     # Max num of prompts if invalid  
> file selected
>
>
> if test -z $work_dir -o -z "$prompt"
> then
>    echo "$(basename $0):  Missing arguments!" > /dev/stderr
>    exit $E_NEED_ARGS
> elif test ! -e $work_dir
> then
>    echo "$(basename $0):  \"$work_dir\" does not exist!" > /dev/stderr
>    exit $E_FILE_DOES_NOT_EXIST
> elif test ! -d $work_dir
> then
>    echo "$(basename $0):  \"$work_dir\" is not a directory!" > /dev/ 
> stderr
>    exit $E_FILE_NOT_DIR
> elif test ! -x $work_dir
> then
>    echo "$(basename $0):  You do not have permission to list the  
> files in \"$work_dir\"!" > /dev/stderr
>    exit $E_PERM_DENIED
> fi
>
> if test -z $full_pathQQQ
> then
>    full_pathQQQ=1
> fi
>
> # --------------------------------------------------------- #
> # --------------------------------------------------------- #
>
> command ls $work_dir | grep -n -v 'randtonotmatch' | column > /dev/ 
> stderr
> num_files=$(command ls $work_dir | grep -c -v 'randtonotmatch')
> digits=1
> while (( $num_files >= 10 ))
> do
>    ((digits += 1))
>    ((num_files /= 10))
> done
> tries=0
> while [ ! -e "$chosen_file" -o $tries != $max_tries ]
> do
>    read -p "$prompt:   " -n $digits chosen_num > /dev/stderr
>    chosen_file=$(command ls $work_dir | grep -n -v 'randtonotmatch'  
> | grep ^$(($chosen_num)): | cut -d ":" -f 2-)
>    if [ ! -e $chosen_file ]
>     then
>       ((tries += 1))
>       echo -e "\nInvalid file selection!  You have $((max_tries -  
> tries)) left."
>    fi
> done
>
> if (( $max_tries = $tries ))
> then
>    echo "$(basename $0):  You have repeatedly chosen an invalid  
> file!  This program will now quit." > /dev/stderr
>    exit $E_INVALID_USER_INPUT
> #      echo "$(basename $0):  The chosen file does not exist!" > / 
> dev/stderr
> fi
> echo " - $chosen_file" > /dev/stderr
> echo $chosen_file >&1


Also, what would be the best way to have a timeout period on prompts  
using the command "read"?  I want it to automatically choose what the  
user has entered after 0.5 seconds.  This is actually for a different  
script.  Also, if possible, it would be nice to have that timeout  
period restart if the user types anything.


Thank you very much to anyone who responds.
~Matt

PS: In case it would help, here is the version of this from before I  
tried to implement "retries".

> #!/bin/bash
>
> #************************************************#
> #                 file_prompt.sh                 #
> #        written by Matthew Strax-Haber          #
> #             Started June 19, 2005              #
> #          Last Modified June 23, 2005           #
> #                                                #
> #         Lists files in a dir and asks          #
> #            the user which to select            #
> #************************************************#
>
> E_FILE_DOES_NOT_EXIST=85
> E_PERM_DENIED=87
> E_FILE_NOT_DIR=88
> E_NEED_ARGS=95
> work_dir=$1                     # directory to work in
> prompt=${2-"Choose"}            # prompt to show user
> full_pathQQQ=$3                 # whether output should be full path
> #chosen_num                     # Num from prompt
> #chosen_file                    # Name of chosen file
>
>
> if test -z $work_dir -o -z "$prompt"
> then
>    echo "$(basename $0):  Missing arguments!" > /dev/stderr
>    exit $E_NEED_ARGS
> elif test ! -e $work_dir
> then
>    echo "$(basename $0):  \"$work_dir\" does not exist!" > /dev/stderr
>    exit $E_FILE_DOES_NOT_EXIST
> elif test ! -d $work_dir
> then
>    echo "$(basename $0):  \"$work_dir\" is not a directory!" > /dev/ 
> stderr
>    exit $E_FILE_NOT_DIR
> elif test ! -x $work_dir
> then
>    echo "$(basename $0):  You do not have permission to list the  
> files in \"$work_dir\"!" > /dev/stderr
>    exit $E_PERM_DENIED
> fi
>
> if test -z $full_pathQQQ
> then
>    full_pathQQQ=1
> fi
>
> # --------------------------------------------------------- #
> # --------------------------------------------------------- #
>
> if test -O $work_dir -a -d $work_dir
> then
>    command ls $work_dir | grep -n -v 'randtonotmatch' | column > / 
> dev/stderr
>    num_files=$(command ls $work_dir | grep -c -v 'randtonotmatch')
>    echo $num_files > /dev/stderr
>    digits=1
>    while (( $num_files >= 10 ))
>     do
>       ((digits += 1))
>       ((num_files /= 10))
>     done
>    read -p "$prompt:   " -n $digits chosen_num > /dev/stderr
>    chosen_file=$(command ls $work_dir | grep -n -v 'randtonotmatch'  
> | grep ^$(($chosen_num)): | cut -d ":" -f 2-)
>
>    if [ ! -e $chosen_file ]
>     then
>       echo "$(basename $0):  The chosen file does not exist!" > / 
> dev/stderr
>    fi
>
>    echo " - $chosen_file" > /dev/stderr
>    echo $chosen_file >&1
> fi
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