CODEWITHSUNDEEP
bashshellhttpcurl
mehmet riza oz
mehmet riza oz

Reputation: 559

How to check content type using curl in shell

I want to check content type of a file in a server. Following code always echoes "image size is invalid".

    TYPE=$(curl -sI $IMAGE_LINK | grep Content-Type)
    IFS=" "
    set $TYPE
    echo $2

    if [ $2 == "image/gif" ] 
    then
        echo "image size is valid"
        exit 0  
    else
        echo "image size is invalid"
        exit 1
    fi

This is the output. Why comparison does not work when $2 is "image/gif"? 

image/gif
image size is invalid

Additionally, This is my unwanted solution.

    TYPE=$(curl -sI $IMAGE_LINK | grep "Content-Type: image/gif")
    echo $TYPE

    if [ ! "$TYPE" = "" ]

Upvotes: 1

Views: 1352

Answers (3)

John Szakmeister
John Szakmeister

Reputation: 47032

The comparison doesn't work because there is a trailing carriage return at the end of $2. You can see it if you do this:

TYPE=$(curl -sI $IMAGE_LINK | grep Content-Type)
IFS=" "
set $TYPE
echo -n "$2" | od -t c

Which will yield:

0000000    i   m   a   g   e   /   g   i   f  \r
0000012

Also, setting IFS isn't really helping you here since space is included in the default IFS setting. You could set IFS to include the carriage return (IFS=$' \r'), or use another way to parse out the bit you need:

TYPE=$(curl -sI "$IMAGE_LINK" | grep Content-Type | tr -d '\r' | cut -f 2 -d ' ')
if [ "$TYPE" = "image/gif" ]
then
    echo 'It works!'
fi

Or, even better (as suggested by @DanielStenberg):

TYPE=$(curl -sI "$IMAGE_LINK" -w '%{content_type}' -o /dev/null)
if [ "$TYPE" = "image/gif" ]
then
    echo 'It works!'
fi

Upvotes: 1

Daniel Stenberg
Daniel Stenberg

Reputation: 58014

Extracting the Content-Type: header can be done with just curl and the -w option, like in this shell script:

type=$(curl -sI "$IMAGE_LINK" -o/dev/null -w '%{content_type}\n')

if [ "$type" = "image/gif" ]
then
    echo "image type is valid"
    exit 0  
else
    echo "image type is invalid"
    exit 1
fi

Upvotes: 7

anubhava
anubhava

Reputation: 785156

Instead of grep and IFS, set etc, you can use a single awk to extract Content-Type header:

type=$(curl -sI "$IMAGE_LINK" | awk -F ': ' '$1 == "Content-Type" { print $2 }')

if [[ $type == *"image/gif"* ]] 
then
    echo "image size is valid"
    exit 0  
else
    echo "image size is invalid"
    exit 1
fi

Upvotes: 2

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