[SOLVED]Questions about a shell program and about shell: files, regexp

Question

Hello, I'm writing this little program in shell:
#!/bin/bash
# Synopsis:
# Read from an inputfile each line, which has the following format:
# lllnn nnnnnnnnnnnnllll STRING lnnnlll n nnnn nnnnnnnnn nnnnnnnnnnnnnnnnnnnn ll ll
# where:
# n is a <positive int>
# l is a <char> (no special chars)
# the last set of ll ll could be:
# - NV
# - PV
# Ex:
# AVO01 000060229651AVON FOOD OF ARKHAM C A S060GER 0 1110 000000022 00031433680006534689 NV PV
# The program should check, for each line of the file, the following:
# I) If the nn of character lllnn (beggining the line) is numeric,
# this is, <int>
# II) If the character ll ll is NV (just one set of ll) then
# copy that line in an outputfile, and add one to a counter.
# III) If the character ll ll is NP (just one set of ll) then
# copy that line in an outputfile, and add one to a counter.
# NOTICE: could be just one ll. Ex: [...] NV [...]
# [...] PV [...]
# or both Ex: [...] NV PV [...]
# Execution (after generating the executable):
# ./ inputfile outputfileNOM outputfilePGP
# Check the number of arguments that could be passed.
if [[ ${#@} != 3 ]]; then
echo "Error...must be: myShellprogram <inputfile> <outputfileNOM> <outputfilePGP>\n"
exit
fi
#Inputfile: is in position 1 on the ARGS
inputfile=$1
#OutputfileNOM: is in position 2 on the ARGS
outputfileNOM=$2
#OutputfilePGP: is in position 3 on the ARGS
outputfilePGP=$3
#Main variables. Change if needed.
# Flags the could appear in the <inputfile>
# ATTENTION!!!: notice that there is a white space
# before the characters, this is important when using
# the regular expression in the conditional:
# if [[ $line =~ $NOM ]]; then [...]
# If the white space is NOT there it would match things like:
# ABCNV ... which is wrong!!
NOM=" NV"
PGP=" PV"
#Counters of ocurrences
countNOM=0;
countPGP=0;
#Check if the files exists and have the write/read permissions
if [[ -r $inputfile && -w $outputfileNOM && -w $outputfilePGP ]]; then
#Read all the lines of the file.
while read -r line
do
code=${line:3:2} #Store the code (the nnn) of the "llnnn" char set of the inputfile
#Check if the code is numeric
if [[ $code =~ ^[0-9]+$ ]] ; then
#Check if the actual line has the NOM flag
if [[ $line =~ $NOM ]]; then
echo "$line" >> "$outputfileNOM"
(( ++countNOM ))
fi
#Check if the actual line has the PGP flag
if [[ $line =~ $PGP ]]; then
echo "$line" >> "$outputfilePGP"
(( ++countPGP ))
fi
else
echo "$code is not numeric"
exit
fi
done < "$inputfile"
echo "COUN NON $countNOM"
echo "COUN PGP $countPGP"
else
echo "FILE: $inputfile does not exist or does not have read permissions"
echo "FILE: $outputfileNOM does not exist or does not have write permissions"
echo "FILE: $outputfilePGP does not exist or does not have write permissions"
fi
I have some questions:
I) When I do:
if [[ -r $inputfile && -w $outputfileNOM && -w $outputfilePGP ]]; then
else
echo "FILE: $inputfile does not exist or does not have read permissions"
echo "FILE: $outputfileNOM does not exist or does not have write permissions"
echo "FILE: $outputfilePGP does not exist or does not have write permissions"
fi
I would like to print the things on the else, accordingly, this is, print the right message. Ex: if "$outputfileNOM" did not have the write permission, just print that error. BUT, I don't want to put a lot of if/else, Ex:
if [[ -r $inputfile ]]; then
if [[-w $outputfileNOM ]] then
else
For the READ permission, and the other for the WRITE
Is there a way to do it, without using a nesting approach, and that maintains the readability. 
II) About the:
if [[ -r $inputfile && -w $outputfileNOM && -w $outputfilePGP ]]
is OK if I use the flag "-x" instead of -r or -w. I don;t have a clear definition of what is the meaning of:
-x FILE
FILE exists and execute (or search) permission is granted
III) Notice the ATTENTION label in my code. I notice that there are some possibilities, for ex: having white spaces before, after or before or after. I'm believing in the consistency of the input files, but if they change, it will explode. What could I do in this case? Is there an elegant way to manage it? (exceptions?)
Thank you very much!
EDIT: corrected what rockin turtle wrote bellow about the format. Thank you.
Last edited by gromlok (2011-10-09 18:39:03)

Answer 1

I) Regarding your if statement, you could do something like this:
estr='FILE: %s does not exist or does not have %s permissions.\n'
[ -r $inputfile ] || ( printf "$estr" "$inputfile" "read" && exit 1 )
[ -w $outputfileNOM ] || ( printf "$estr" "$outputfileNOM" "write" && exit 1 )
[ -w $outputfilePGP ] || ( printf "$estr" "$outputfilePGP" "write" && exit 1 )
II)The -r/-w/-x mean that the file has the read/write/execute bit set. Do a
$ man chmod
for details.
III) You should be able to do
if [[ "$line" =~ .*\<NV\> ]]; then
echo "..."
(( countNOM++ ))
fi
but that didn't work for me when I tried it.  I don't know if this is a bug in bash, or (more likely) something that I am doing wrong.
Regardless, I would write your script like this:
#!/bin/bash
file=$(egrep '^[A-Z]..[0-9]{2}' "$1")
grep '\<NV\>' <<< "$file" > "$2"
grep '\<PV\>' <<< "$file" > "$3"
echo 'Count NON:' $(wc -l < "$2")
echo 'Count PGP:' $(wc -l < "$3")
Note: In reading your script, your comments imply that each line of the input file starts with 'llnnn' but the example line you gave starts with 'lllnn'.  That is, there are 3 letters (AVO) followed by 2 numbers (01). The above script assumes that lines start with 'lllnn'