Check if a program exists in bash

Question

I am trying to check if md5sum or digest exists on solaris and script is used on different machines.

Here is the function in sh script which is called from a ksh script

getMD5cmd ()
{
    PATH="${PATH}:/bin:/usr/bin:/usr/sfw/bin:/usr/local/bin:/usr/sbin/bin"
    if type -p md5sum;then
        MD5CMD=`type -p md5sum`
    elif type -p digest;then
        MD5CMD="`type -p digest` -a md5"
    fi
    echo "HERE ${MD5CMD}"
}

When I run scripts I get

-p not found
md5sum not found
-p not found
digest is /bin/digest
HERE

However, when I type it in a terminal, works as exptected

Any Ideas? Thanks

Answer 1

Have you tried the following syntax:

MD5CMD="$(type -p md5sum digest |sed -e 's/digest$/digest -a md5/' |head -1)"
if [ -z "$MD5CMD" ]; then
    echo 'no md5 sum command found' >&2
    exit 1
fi
echo "HERE $MD5CMD"

I tried this in Cygwin and type will return multiple rows, so it works.

Answer 2

if which md5sum >/dev/null 2>&1; then
    md5cmd="md5sum"
elif  which digest >/dev/null 2>&1; then
    md5cmd="digest -a md5"
else
    echo "No md5 command found" >&2
    exit 1
fi

$md5cmd YOUR_FILE

Answer 3

You are likely running ksh or possibly Bash for your interactive shell. Both of these have a -p option for type. The shell (probably sh) that your script is running in has type but doesn't have the -p option so it's looking for "-p" as the name of an executable and it doesn't find it.

So you could change your script to use ksh or you could use the which program. The latter is probably more portable, since some systems don't have ksh.

Answer 4

As you are setting the PATH, knowing where precisely the command is seems unnecessary.

getMD5cmd ()
{
    PATH=${PATH}:/bin:/usr/bin:/usr/sfw/bin:/usr/local/bin:/usr/sbin/bin
    md5sum /dev/null >/dev/null 2>&1 && MD5CMD=md5sum || MD5CMD="digest -a md5"
    echo "HERE ${MD5CMD}"
}
getMD5cmd