Trying to do a script to download a file using wget, or curl if wget doesn't exist in Linux. How do I have the script check for existence of wget?
Linux has a which
command which will check for the existence of an executable on your path:
pax> which ls ; echo $?
/bin/ls
0
pax> which no_such_executable ; echo $?
1
As you can see, it sets the return code $?
to easily tell if the executable was found.
wget http://download/url/file 2>/dev/null || curl -O http://download/url/file
One can also use command
or type
or hash
to check if wget/curl exists or not. Another thread here - " Check if a program exists from a Bash script " answers very nicely what to use in a bash script to check if a program exists.
I would do this -
if [ ! -x /usr/bin/wget ] ; then
# some extra check if wget is not installed at the usual place
command -v wget >/dev/null 2>&1 || { echo >&2 "Please install wget or set it in your path. Aborting."; exit 1; }
fi
First thing to do is try install to install wget
with your usual package management system,. It should tell you if already installed;
yum -y wget
Otherwise just launch a command like below
wget http://download/url/file
If you receive no error, then its ok.
A solution taken from the K3S install script (https://raw.githubusercontent.com/rancher/k3s/master/install.sh )
function download {
url=$1
filename=$2
if [ -x "$(which wget)" ] ; then
wget -q $url -O $2
elif [ -x "$(which curl)" ]; then
curl -o $2 -sfL $url
else
echo "Could not find curl or wget, please install one." >&2
fi
}
# to use in the script:
download https://url /local/path/to/download
Explanation: It looks for the location of wget
and checks for a file to exist there, if so, it does a script-friendly (ie quiet) download. If wget isn't found, it tries curl
in a similarly script-friendly way.
(Note that the question doesn't specify BASH however my answer assumes it.)
Simply run
wget http://download/url/file
you will see the statistics whether the endpoint is available or not.
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