Shell Script Showing Error Message When Redirecting Echo Within If-Else Statements

Question

I am trying to redirect the output to a file within if-else statements but it is not working with me. Here's what I am doing

$1=1    
output="/home/file.txt" 
if [[ $1 -gt 5 ]] 
then 
echo "$1 is greater than 5" > $output #this is working with me 
else 
echo "$1 is not greater than 5" > $output #this is giving me "ambiguous redirect" 
fi

Any idea what the issue may be? I tried puting $output between double quotes, but I got a different error message:

if [[ $1 -gt 5 ]] 
then 
echo "$1 is greater than 5" > "$output" #this is working with me 
else 
echo "$1 is not greater than 5" > "$output" #this is giving me "No such file or directory" 
fi

Possible duplicate of [Getting an "ambiguous redirect" error](https://stackoverflow.com/questions/2462385/getting-an-ambiguous-redirect-error) — Ikaros, Mar 13 '18 at 13:00
Can you verify that you get this error with the code as posted? It looks like you modified the script before posting, but didn't check that the error is still the same — that other guy, Mar 13 '18 at 15:25

Abhijit Pritam Dutta · Answer 1 · 2018-03-13T15:46:05.263

-1

First of all never use $1 till $9 as variable in your script (also never declare variable with $). These are Unix/Linux system variable and these variable use by Unix/Linux to store the command line parameters:

For example:-

    yourshellscript.sh hello word!

    echo $1" "$2 # this will print hello world!

I have modified your script which will work for you

#!/bin/bash  
#always put this line at the top of your shell script this indicate in 
#which shell this script should run in this case it is bash shell. This is 
#very important because each shall has different syntax for if, while 
#condition and numeric expression.
NUMBER=1
output="/home/file.txt"
if [ $NUMBER -gt 5 ]
then
    echo "$NUMBER is greater than 5" > $output #this is working with me
else
    echo "$NUMBER is not greater than 5" > $output #this is giving me "ambiguous redirect"
fi

Also you can enter a number from consul like below:-

NUMBER=1
read -p "Enter a Number : " NUMBER     
output="/home/file.txt"
if [ $NUMBER -gt 5 ]
then
    echo "$NUMBER is greater than 5" > $output #this is working with me
else
    echo "$NUMBER is not greater than 5" > $output #this is giving me "ambiguous redirect"
fi

edited Mar 13 '18 at 15:46

answered Mar 13 '18 at 11:59

Abhijit Pritam Dutta

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Your variable naming is inconsistent. Also, you should explain whiy what you are doing works and what's the difference with OP's script – Ikaros Mar 13 '18 at 12:32
Also you don't need to put double brackets `[[ ]] `, you can use single brackets `[ ]`. – Ikaros Mar 13 '18 at 12:33
@lkaros yes true but that will not produce any error just an extra unnecessary `]`. But that should not be the reason for down vote. I am just changing the script of OP he knew what was he doing. This is just an example not a script in a system – Abhijit Pritam Dutta Mar 13 '18 at 12:42
My bad about the brackets, didn't notice them in OP's script. Still, you should add *why* your script does work and OP's doesn't – Ikaros Mar 13 '18 at 12:55
I already mentioned. He was using $1 for which it was not working. Correct it and run it in my system which is working. – Abhijit Pritam Dutta Mar 13 '18 at 12:57
Doesn't work for me. I get `myscript: line 6: =1: command not found` and `myscript: line 8: [: -gt: unary operator expected` – that other guy Mar 13 '18 at 15:39
Try now it will work. Modify `$NUMBER=1` to `NUMBER=1` – Abhijit Pritam Dutta Mar 13 '18 at 15:46
Never declare variable with $ – Abhijit Pritam Dutta Mar 13 '18 at 15:48

Shell Script Showing Error Message When Redirecting Echo Within If-Else Statements

1 Answers1