Синтаксическая ошибка ожидается операнд неверный маркер

I have the following bash script # 1 + x^2/2! + x^4/4! + ... + x^(2n)/(2*n)! #!/bin/bash factorial() { n=$1 fact=1 for ((i = 2; i <= $n; i++)); do fact=$(expr $fact * $i) ...

The error message is caused by the line a=$(($ex / $f)), because there is no operand following the / (divide) operator. So the immediate suspicion is that the variable f is an empty string.

The cause of that is the behaviour of the $( ) command substitution when f is assigned. This collects the contents of stdout when the enclosed command pipeline is executed. As your factorial() function writes nothing to stdout, the value assigned to f is empty. The solution is to echo or print the value, in place of the return — e.g. as printf '%sn' "${fact}".

Some additional notes that might be helpful:

The value in the return statement represents the status of the function, not any data it may have produced. In the absence of a return statement, the exit status of the last command executed in the function is passed back to the caller.

The return status is truncated to 8 bits, and is unsigned, so it can only take the range 0-255.

In addition, the status of external commands has further conventions. Processes terminated by a signal get a status of 128 + the signal number. If the shell fails to create a new process, or to execute the command, 126 or 127 may be returned. Status 0 is conventionally success, and any small integer from 1 up indicates a command-detected error or unusual result. I would consider it wise to follow the same conventions in my shell functions, and never to return a data value this way.

Shell arithmetic is (according to the GNU/bash manual) evaluated in fixed-width integers. On my system, that appears to be 64-bit signed integers, but it may vary across systems and distros. 31 bits is only sufficient to hold 12!, and 63 bits only holds 20!, which may limit your scope.

This fragment shows Bash arithmetic overflowing 63 bits, somewhere around 9.22e+18.

Paul--) for k in {1..10}; do
> printf '%s %sn' $k $(( 3000000000000000000 * k ))
> done
1 3000000000000000000
2 6000000000000000000
3 9000000000000000000
4 -6446744073709551616
5 -3446744073709551616
6 -446744073709551616
7 2553255926290448384
8 5553255926290448384
9 8553255926290448384
10 -6893488147419103232
Paul--) 

My go-to for large numbers is the dc command, which does unconstrained numeric size, but requires RPN (reverse polish notation). This fragment generates the RPN commands to list factorials up to 10!

Paul--) { echo 1; seq -s ' p * p ' 2 10; echo ' p * p q'; }
1
2 p * p 3 p * p 4 p * p 5 p * p 6 p * p 7 p * p 8 p * p 9 p * p 10
 p * p q
Paul--) 

and this is the execution (but I tested up to 400!):

Paul--) { echo 1; seq -s ' p * p ' 2 10; echo ' p * p q'; } | dc
2
2
3
6
4
24
5
120
6
720
7
5040
8
40320
9
362880
10
3628800
Paul--) 

I’m writing a script in bash and I get this error:

./P4.1: line 10: +: syntax error: operand expected (error token is "+")

And this is my code:

#!/bin/bash
read string
echo $string >| temp
num1= cut -d" " -f1 temp
num2= cut -d" " -f2 temp
num3= cut -d" " -f3 temp
while [ $num1 -gt $num3 ]
do
        echo $num1
        num1=$[$num1+$num2]
done

What’s wrong and how do I fix it?
Thanks.

asked Nov 24, 2013 at 16:03

shoham's user avatar

1

Combination of ceving and Tomek’s:

#!/bin/bash
read num1 num2 num3
while [ $num1 -lt $num3 ]
do
    echo $num1
    num1=$((num1+num2))
done

answered Nov 24, 2013 at 16:32

Blue Ice's user avatar

Blue IceBlue Ice

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4

Use round parenthesis for numeric computations:

num1=$((num1 + num2))

BoltClock's user avatar

BoltClock

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answered Nov 24, 2013 at 16:10

ceving's user avatar

cevingceving

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0

#!/bin/bash
read string
echo "${string}" >| temp
num1= cut -d" " -f1 temp
num2= cut -d" " -f2 temp
num3= cut -d" " -f3 temp
while [ "${num1}" -gt "${num3}" ]
do
    echo "${num1}"
    num1=$(expr "${num1}" + 1)
done

also, quote and brace your variables. :D

answered Nov 24, 2013 at 16:09

petrus4's user avatar

petrus4petrus4

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0

try
num1=$[ num1 + num2 ]
may remove the error ~

answered Jun 30, 2022 at 1:49

Maplefrost's user avatar

I am getting this error bellow:

Path to the shell file:line 6: ++++: syntax error: operand expected (error token is "+")

and

Path to the shell file:line 13: ((: i <= : syntax error: operand expected (error token is "<= ")

This is my script:

#!/bin/bash  
SCRIPTPATH=$( cd $(dirname $0) ; pwd -P )
file="$SCRIPTPATH/android/sdcard.img"
file2="$SCRIPTPATH/android/devices.txt"

TOTALDEVICES=$(($1+$2+$3+$4+$5))
ANDROID4=0
ANDROID5=0
ANDROID5_1=0
ANDROID6=0
ANDROID7=0
echo $TOTALDEVICES
for ((i = 1; i <= $TOTALDEVICES; i++));

do
   if (($1 > 0 && $ANDROID4 < $1)) 
   then 
   echo "Device$i PACKAGE(avd4.4) 1"
   ANDROID4=$((ANDROID4 + 1))
    echo "no" |~/Android/Sdk/tools/bin/avdmanager create avd -f --package 'system-images;android-19;google_apis;armeabi-v7a' --name "avd4"  --tag 'google_apis' -p $SCRIPTPATH/android/avd4
   fi

   if (($2 > 0 && $ANDROID5 < $2 && $ANDROID4 == $1 && $i > $ANDROID4))
   then 
   echo "Device$i PACKAGE(avd5.0) 2"
   ANDROID5=$((ANDROID5 + 1))
    echo "no" |~/Android/Sdk/tools/bin/avdmanager create avd -f --package 'system-images;android-21;google_apis;armeabi-v7a' --name "avd5"  --tag 'google_apis' -p $SCRIPTPATH/android/avd5
   fi
   if (($3 > 0 && $ANDROID5_1 < $3 && $ANDROID5 == $2 && $i > $ANDROID5 + $ANDROID4))
   then 
   echo "Device$i PACKAGE(avd5.1) 3"
   ANDROID5_1=$((ANDROID5_1 + 1))
    echo "no" |~/Android/Sdk/tools/bin/avdmanager create avd -f --package 'system-images;android-22;google_apis;x86' --name "avd5.1"  --tag 'google_apis' -p $SCRIPTPATH/android/avd5.1
   fi
   if (($4 > 0 && $ANDROID6 < $4 && $ANDROID5_1 == $3 && $i > $ANDROID5_1 + $ANDROID5 + $ANDROID4))
   then 
   echo "Device$i PACKAGE(avd6) 4"
   ANDROID6=$((ANDROID6 + 1))
   echo "no" | ~/Android/Sdk/tools/bin/avdmanager create avd -f --package 'system-images;android-23;google_apis;x86' --name "avd6"  --tag 'google_apis' -p $SCRIPTPATH/android/avd6
   fi
   if (($5 > 0 && $ANDROID7 < $5 && $ANDROID6 == $4 && $i > $ANDROID6 + $ANDROID5_1 + $ANDROID5 + $ANDROID4))
   then 
   echo "Device$i PACKAGE(avd7) 5"
   ANDROID7=$((ANDROID7 + 1))
   echo "no" | ~/Android/Sdk/tools/bin/avdmanager create avd -f --package 'system-images;android-24;google_apis;x86' --name "avd7"  --tag 'google_apis' -p $SCRIPTPATH/android/avd7  
   fi
done

AVDMANAGEROUTPUT=$(~/Android/Sdk/tools/bin/avdmanager list avds | grep "Name:")
AVDMANAGEROUTPUT=${AVDMANAGEROUTPUT//$'n'/} # Remove all newlines.
AVDMANAGEROUTPUT=${AVDMANAGEROUTPUT%$'n'}   # Remove a trailing newline.
DEVICES=()
i=0
IFS=' ' read -r -a array <<< "$AVDMANAGEROUTPUT"
for index in "${!array[@]}"
do
    rem=$(( $index % 2 )) #check for odd number to avoid Name:
    if [ $rem -eq 1 ]
    then
        echo "${array[index]}" #Now put values into an array
        DEVICES[$i]=`echo @"${array[index]}"`
        i=$((i+1))
    fi
done
# Check if the sdcard is available
if [ -f "$file" ]
then
    echo "$file found."
    ~/Android/Sdk/emulator/emulator ${DEVICES[0]} -sdcard $file >> "$SCRIPTPATH/emulators.txt" 2>&1 & #open the emulator
    ~/Android/Sdk/emulator/emulator ${DEVICES[1]} -sdcard $file >> "$SCRIPTPATH/emulators.txt" 2>&1 & #open the emulator
    ~/Android/Sdk/emulator/emulator ${DEVICES[2]} -sdcard $file >> "$SCRIPTPATH/emulators.txt" 2>&1 & #open the emulator
    ~/Android/Sdk/emulator/emulator ${DEVICES[3]} -sdcard $file >> "$SCRIPTPATH/emulators.txt" 2>&1 & #open the emulator
    ~/Android/Sdk/emulator/emulator ${DEVICES[4]} -sdcard $file >> "$SCRIPTPATH/emulators.txt" 2>&1 & #open the emulator
    sleep 110
else
# if there is none,here we are creating one
    echo "$file not found."
    ~/Android/Sdk/emulator/mksdcard 10G "$SCRIPTPATH/android/sdcard.img"
    sleep 5
    ~/Android/Sdk/emulator/emulator ${DEVICES[0]} -sdcard $file  >> "$SCRIPTPATH/emulators.txt" 2>&1 &  
    ~/Android/Sdk/emulator/emulator ${DEVICES[1]} -sdcard $file >> "$SCRIPTPATH/emulators.txt" 2>&1 & #open the emulator
    ~/Android/Sdk/emulator/emulator ${DEVICES[2]} -sdcard $file >> "$SCRIPTPATH/emulators.txt" 2>&1 & #open the emulator
    ~/Android/Sdk/emulator/emulator ${DEVICES[3]} -sdcard $file >> "$SCRIPTPATH/emulators.txt" 2>&1 & #open the emulator
    ~/Android/Sdk/emulator/emulator ${DEVICES[4]} -sdcard $file >> "$SCRIPTPATH/emulators.txt" 2>&1 & #open the emulator
    sleep 110
fi

Zanna's user avatar

Zanna

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asked May 4, 2017 at 6:41

Sibabalwe Mvelo's user avatar

1

Line 6 of your script expects arguments 1 to 5 to exist. If you run your script with no arguments $1+$2+$3+$4+$5 will become +++++ which explains the error message. (A similar explanation is valid for the second error message.) Perhaps you should check that 5 arguments have been provided and exit with an error message if this test fails, e. g.:

if [ $# != 5 ]
then
    echo "Usage: scriptname num1 num2 num3 num4 num5"
    exit 2
fi

Alternatively you can provide a default value for missing arguments with Bash’s parameter expansion. In the following expression the first 5 command-line arguments, or 0 in their absence, are added to a sum:

$((${1-0} + ${2-0} + ${3-0} + ${4-0} + ${5-0}))

Note that you should also check that each of the 5 arguments is numeric before attempting to obtain their sum.

David Foerster's user avatar

answered May 4, 2017 at 9:00

Jeffrey Ross's user avatar

Thank you for your answer, you helped me see what I did wrong.

How did I fix it:

I then ran the sh file like ‘file.sh’ 1 1 1 1 1 which had enabled the emulators to run. The 1s determine how many emulators of each do I want to run.

answered May 9, 2017 at 13:51

Sibabalwe Mvelo's user avatar

0

Could anyone point out what’s wrong with the below line from a bash script I’m using?

if [ "$(( $(date +"%s")-$(stat -c "%Y" $SENDDIR/$NIGHTLY_FILE) ))" -gt "3600" ]; then

I receive the error noted in the subject line.

I had copied the script from one server to another thinking that it should work but alas, no.

  • bash
  • operand

Josh Crozier's user avatar

Josh Crozier

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asked Dec 9, 2013 at 1:45

PeteJ's user avatar

PeteJPeteJ

13 bronze badges

5

  • wrap that line with set -vx above and set +vx below so you can see how the variables are being expanded. Then it should be very easy to see where the problem is with you math values. Good luck.

    Dec 9, 2013 at 2:12

  • Hi @shellter, Thanks for the input. With that enabled this is the output: date +»%s») -$(stat -c «%Y» $SENDDIR/$NIGHTLY_FILE) date +»%s» ++ date +%s stat -c «%Y» $SENDDIR/$NIGHTLY_FILE) stat -c «%Y» $SENDDIR/$NIGHTLY_FILE ++ stat -c %Y /senddir/nightly_file.xml stat: cannot stat /senddir/nightly_file.xml’: No such file or directory ./file.sh: line 75: 1386560712 — : syntax error: operand expected (error token is «- «) I’ve looked it over but am not sure how to interpret the output. edit: Apologies about the lack of formatting.

    Dec 9, 2013 at 3:52

  • Does /senddir/nightly_file.xml exist? The error seems to indicate otherwise.

    Dec 9, 2013 at 4:41

  • Hi Michael. Bingo. The rudimentary script was fine. A particular directory the script relies on was not where it should have been on the new server. Thank you both for the input!

    Dec 9, 2013 at 22:48

Could anyone point out what’s wrong with the below line from a bash script I’m using?

if [ "$(( $(date +"%s")-$(stat -c "%Y" $SENDDIR/$NIGHTLY_FILE) ))" -gt "3600" ]; then

I receive the error noted in the subject line.

I had copied the script from one server to another thinking that it should work but alas, no.

  • bash
  • operand

Josh Crozier's user avatar

Josh Crozier

228k54 gold badges386 silver badges301 bronze badges

asked Dec 9, 2013 at 1:45

PeteJ's user avatar

PeteJPeteJ

13 bronze badges

5

  • wrap that line with set -vx above and set +vx below so you can see how the variables are being expanded. Then it should be very easy to see where the problem is with you math values. Good luck.

    Dec 9, 2013 at 2:12

  • Hi @shellter, Thanks for the input. With that enabled this is the output: date +»%s») -$(stat -c «%Y» $SENDDIR/$NIGHTLY_FILE) date +»%s» ++ date +%s stat -c «%Y» $SENDDIR/$NIGHTLY_FILE) stat -c «%Y» $SENDDIR/$NIGHTLY_FILE ++ stat -c %Y /senddir/nightly_file.xml stat: cannot stat /senddir/nightly_file.xml’: No such file or directory ./file.sh: line 75: 1386560712 — : syntax error: operand expected (error token is «- «) I’ve looked it over but am not sure how to interpret the output. edit: Apologies about the lack of formatting.

    Dec 9, 2013 at 3:52

  • Does /senddir/nightly_file.xml exist? The error seems to indicate otherwise.

    Dec 9, 2013 at 4:41

  • Hi Michael. Bingo. The rudimentary script was fine. A particular directory the script relies on was not where it should have been on the new server. Thank you both for the input!

    Dec 9, 2013 at 22:48

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