importing data from a text file to a bash script

Question

I need to import a text file like this below:

AMBI
CBNK
CCXI
CERE
CLACW
CNYD
DAEG
DLIA
DLLR
DNDN
DSGX
HAST
HIBB,
HPOL
IRDMZ
MARK
NEPT
NFEC
NINE
NRCIB
OMER
PLCC
PLPM
PSUN
UNTK

There are 25 entries, I need to pass them into a bash script.

I want to run the program once for each symbol. The symbols are Nasdaq stock symbols. I'm trying to pull a quote with the script.

I've been able to do this command manually:

sh stock (symbol) > /home/user/Desktop/stockquote.txt

by inputting the (symbol) manually, I need a a script to do it automatically.

Answer 1

Are you trying to read each line as the symbol?

Have the 25 entries be in a file called stocks.txt. Then use the following script to iterate over each line in the stocks file and process the symbol using the stock function declared in the same script:

while read symbol ; do 
  stock $symbol >> /home/user/Desktop/stockquote.txt 
done < stocks.txt

Answer 2

Apparently, the title and the body of the question did not seem quite the same to me. Here are two solutions:

Importing data from an external file into a Bash script:

Read the file and store its contents as entries in an array. (Note: this is feasible given the contents of your text file. If, for e.g., any line in the file had multiple words without quotations, the array so formed would not be as desired.)

declare -a symbols=($(cat input_file.txt | tr '\n' ' '))

Now, iterate over the items of the array symbols as follows.

LOG_FILE=/home/user/Desktop/stockquote.txt    

for symbol in ${symbols[@]}  
do  
    # echo "Processing $symbol ..."  
    sh stock "$symbol" >> "$LOG_FILE"    
done

In fact, you can embed this in the script named stock itself. Just change the sh stock "$symbol" above to something like this:

f_process "$symbol" >> "$LOG_FILE"    

where f_process is possibly a function processing the symbol. If you don't want to write a function, just put the relevant lines of code there.

Passing data from an external file as arguments to a shell script:

A related solution has already been posted by neowulf33. Am just reproducing that with corrections:

LOG_FILE=/home/user/Desktop/stockquote.txt 
while read symbol    
do  
    stock "$symbol" >> "$LOG_FILE"
done < input_file.txt

Answer 3

If you want to loop over the lines of a file, you can use the read builtin in a loop like this:

while IFS= read -r line; do
  echo "$line"
done <input_file.txt

The content of the line is stored in the variable line (you can choose any other name). See Understanding IFS for more explanations. Without IFS=, leading or trailing whitespace is stripped, which may be desirable in your case.

Beware that >stockquote.txt truncates the output file each time. Either put it around the whole command, or use >>stockquote.txt which appends to the file. If you use >>, take care that the file may not be empty when your script starts.

This snippet runs the program stock for each line, and stores the output in stockquote.txt with a blank line (echo with no argument) between each symbol.

while read -r line; do
  stock "$line"
  echo
done <input_file.txt >stockquote.txt

Make sure that stock is executable. If it's a shell script, make sure that it begins with #!/bin/sh. If it isn't in the command search path $PATH, specify the path explicitly (e.g. ./stock if it's in the current directory).

You can also use xargs, but beware that its input syntax is peculiar: it doesn't use newlines as delimiters, but whitespace, and treats \'" as quoting characters (with the default input syntax — just to make things worse, xargs has alternative input syntaxes depending on its command-line options). For your use case, this is probably suitable as well, and it's shorter, but you lose the opportunity to have whitespace or quote characters in symbols, to skip comment lines, etc.

xargs -n 1 stock <input_file.txt >stockquote.txt