syntax error Bash command bc

Question

I am having a problem with the bc command. The output generated is:

(standard_in) 2: syntax error

Here I post my code, any suggestions will be appreciated.

value="100%"          # the threshold to cause a break out
kb="kB/s"
mb="MB/s"             # strings to mask out
conversor=1024        # kb->mb conversion
contador=0            # initalize our total in megabytes
for ((x=3; x<=${#array[@]}; x+=5)); do
    paraula=${array[$x]};

    if [[ $paraula =~ .*kB.* ]]; then
        paraula=${paraula%$kb}
        paraula=$(echo "scale=4; $paraula/$conversor" | bc) # convert to $mb
        contador=$(echo "scale=4; $contador+$paraula" | bc)
        echo "Counting: "$contador
    else
        paraula=${paraula%$mb}
        contador=$(echo "scale=4; $contador+$paraula" | bc)
        echo "Counting: "$contador
    fi

    if [[ " ${array[$x]} " =~ " $value " ]]; then
        break;
    fi
    echo "Value : ${array[$x]} ";

done 

echo "final value: $contador"

then, the error on the terminal after execute the script is

Can you simplify this to a minimal reproducible example? You can probably get the same error from a single line of code that does nothing but invoke bc. — Charles Duffy
– Charles Duffy, Commented Jun 1, 2017 at 18:06
Consider using bash -x yourscript to log everything the script does, to find the place where it first goes wrong. If you want the tracking to be a bit easier, you can assign a value to PS4 that includes line number; for example, all on one line you could run: PS4=':${LINENO}+' bash -x yourscript. (Note that for security reasons, PS4 has to be set inside your script itself in very new versions of bash if that script is running as root). — Charles Duffy
– Charles Duffy, Commented Jun 1, 2017 at 18:07
BTW, please add the above-requested logs as text to the question, not screenshots. See the accepted answer to Why not to upload images of code on SO when asking a question? — Charles Duffy
– Charles Duffy, Commented Jun 1, 2017 at 18:10
Can you echo the values of paraula and contador before you feed it to bc? — Inian
– Inian, Commented Jun 1, 2017 at 18:13
Jesuuuuuuus, that was the problem. On my last row, I added to the counting a %. Thank you so much! — Joan
– Joan, Commented Jun 1, 2017 at 18:17

SaintHax · Accepted Answer · 2017-06-01 18:44:11Z

2

The issue is your last line doesn't have a newline in it, when piped to bc.

This works fine.

$ echo "scale=4; 2046/1024" | bc
1.9980
$ echo -e "scale=4; 2046/1024\n" | bc
1.9980

This is broke

$ echo -n "scale=4; 2046/1024" | bc
(standard_in) 1: syntax error

I think you can change to

contador=$(echo -e "scale=4; $contador+$paraulao\n" | bc)

That should fix it. Also, indent and add comments.

answered Jun 1, 2017 at 18:44

SaintHax

1,95312 silver badges17 bronze badges

Sign up to request clarification or add additional context in comments.

7 Comments

chepner Over a year ago

The -e option is unnecessary (I hope there aren't any escaped characters in what should be numbers).

SaintHax Over a year ago

@chepner the -e is needed for the \n.

chepner Over a year ago

Why use the non-standard -e option to suppress the implicit newline only to add it back explicitly?

chepner Over a year ago

There is no missing newline; echo produces one. Failing to write a newline to bc is a problem, but it's not one the OP is suffering from.

Jeffrey Cash Over a year ago

To avoid potential issues like this and because I think it looks nicer, I tend to just use here strings: bc <<< "scale=4; $contador+$paraula"

|

Collectives™ on Stack Overflow

syntax error Bash command bc

1 Answer 1

7 Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

7 Comments

Your Answer

Sign up or log in

Post as a guest

Related