Es normal encontrarse con archivos pdf con nombres de archivo tan descriptivos como 1606152010.pdf ...
Si el autor asignó un título más apropiado en el campo Title de los metadatos del documento pdf , es posible renombrar éste de forma automática, vamos a ver cómo.

	En Debian puedes encontrar diversas herramientas que permiten visualizar y/o alterar los metadatos de un documento pdf, de forma arbitraria, he elegido la utilidad pdfinfo
	$ pdfinfo 1234567890.pdf    Title: titlepdf    Author: xae    Creator: Writer    Producer: PDFsharp 1.31.178 ...    ...

	Un título
	METADATA=$(pdfinfo "$FILE" 2> /dev/null)    # Title    # Extract    TITLE="${METADATA#Title:*}"    TITLE="${TITLE%%[[.newline.]]*}"    # Trim    TITLE="${TITLE#${TITLE%%[![.space.]]*}}"

	Saneando    Es necesario asegurarse de que el nombre de archivo es seguro, considero que un nombre de archivo es seguro si sólo contiene caracteres alfanuméricos del idioma en uso. Como carácter de reemplazo utilizo el guión bajo.
	# Make path safe    REPLACE_CHAR=_    TITLE="${TITLE//[![:alnum:]]/"$REPLACE_CHAR"}"    # Remove replace char runs    TITLE="${TITLE//+("$REPLACE_CHAR")/"$REPLACE_CHAR"}"

	ya terminamos...
	# Rename    mv -- "$FILE" "$TITLE".pdf

Juntando todas las piezas,

#!/bin/bash
###
# titlepdf
# 
#   Rename pdf file as the title metadata.
#   Makes or not the renaming without error code.
#
#   Dependencies,
#       file
#       pdfinfo
#   
# (c) 2016, xae.
#
# 20160221
###
declare -r SCRIPT=${0##*/}
# depends
# Verify if a dependencie is satisfied,
# if not returns 0.
function depends {
    [ -e $1 ] || 
    {
        printf "%s\n" "$SCRIPT:$LINENO: $1. Not avalaible." >&2 ;
        return 0;
    } 
    return 1
}
# Usage 
# Exits from script with error code 1
function usage {
    printf "$1\nUsage:\n\ttitlepdf pdf_file\n\n" >&2
    exit 1
}
# Dependencies
depends "/usr/bin/file"     ||
depends "/usr/bin/pdfinfo"  &&
exit 1
[ $# -eq 0 ] && usage
shopt -s extglob
for FILE in "$@";
do
    # Test if input is valid
    [[ "$(file -b "$FILE")" =~ 'PDF' ]] ||
         continue
    # Extract metadata
    METADATA=$(pdfinfo "$FILE" 2> /dev/null) ||
         continue
    # Title
    # No title tag
    [ -z "${METADATA##*Title:*}" ] ||
        continue
    # Extract
    TITLE="${METADATA#Title:*}"
    TITLE="${TITLE%%[[.newline.]]*}"
    # Trim
    TITLE="${TITLE#${TITLE%%[![.space.]]*}}"
    # No title
    [ -z "${TITLE}" ] &&
        continue
    # Make path safe
    REPLACE_CHAR=_
    TITLE="${TITLE//[![:alnum:]]/"$REPLACE_CHAR"}"
    # Remove replace char runs 
    TITLE="${TITLE//+("$REPLACE_CHAR")/"$REPLACE_CHAR"}"
    # Rename
    mv -i -- "$FILE" "$TITLE".pdf
done
exit 0

∎

Often you get pdf  files named like 1606152010.pdf ,
a very illustrative title ...
If the author gave a better name in the Title metadata field of the pdf document, renaming the file would be possible , let's do it...

	Debian provides several tools to manage the metadata of a pdf  file, today we will be using pdfinfo
	$ pdfinfo 1234567890.pdf    Title: titlepdf    Author: xae    Creator: Writer    Producer: PDFsharp 1.31.178 ...    ...

	A title
	METADATA=$(pdfinfo "$FILE" 2> /dev/null)    # Title    # Extract    TITLE="${METADATA#Title:*}"    TITLE="${TITLE%%[[.newline.]]*}"    # Trim    TITLE="${TITLE#${TITLE%%[![.space.]]*}}"

	Sanity check    It is a must to test that filenames are secure, by secure is meant a name made of only alphanumeric characters of the current locale. As replace char we are using the underscore.
	# Make path safe    REPLACE_CHAR=_    TITLE="${TITLE//[![:alnum:]]/"$REPLACE_CHAR"}"    # Remove replace char runs    TITLE="${TITLE//+("$REPLACE_CHAR")/"$REPLACE_CHAR"}"

	finishing up...
	# Rename    mv -- "$FILE" "$TITLE".pdf

All pieces together,

#!/bin/bash
###
# titlepdf
# 
#   Rename pdf file as the title metadata.
#   Makes or not the renaming without error code.
#
#   Dependencies,
#       file
#       pdfinfo
#   
# (c) 2016, xae.
#
# 20160221
###
declare -r SCRIPT=${0##*/}
# depends
# Verify if a dependencie is satisfied,
# if not returns 0.
function depends {
    [ -e $1 ] || 
    {
        printf "%s\n" "$SCRIPT:$LINENO: $1. Not avalaible." >&2 ;
        return 0;
    } 
    return 1
}
# Usage 
# Exits from script with error code 1
function usage {
    printf "$1\nUsage:\n\ttitlepdf pdf_file\n\n" >&2
    exit 1
}
# Dependencies
depends "/usr/bin/file"     ||
depends "/usr/bin/pdfinfo"  &&
exit 1
[ $# -eq 0 ] && usage
shopt -s extglob
for FILE in "$@";
do
    # Test if input is valid
    [[ "$(file -b "$FILE")" =~ 'PDF' ]] ||
         continue
    # Extract metadata
    METADATA=$(pdfinfo "$FILE" 2> /dev/null) ||
         continue
    # Title
    # No title tag
    [ -z "${METADATA##*Title:*}" ] ||
        continue
    # Extract
    TITLE="${METADATA#Title:*}"
    TITLE="${TITLE%%[[.newline.]]*}"
    # Trim
    TITLE="${TITLE#${TITLE%%[![.space.]]*}}"
    # No title
    [ -z "${TITLE}" ] &&
        continue
    # Make path safe
    REPLACE_CHAR=_
    TITLE="${TITLE//[![:alnum:]]/"$REPLACE_CHAR"}"
    # Remove replace char runs 
    TITLE="${TITLE//+("$REPLACE_CHAR")/"$REPLACE_CHAR"}"
    # Rename
    mv -i -- "$FILE" "$TITLE".pdf
done
exit 0

∎

Media

	Free Software Foundation, FAL, via Wikimedia Commons
VectorVoyager, via Wikimedia Commons		VectorVoyager, via Wikimedia Commons