How to get the command line args passed to a running process on unix/linux systems?

Question

On SunOS there is pargs command that prints the command line arguments passed to the running process.

Is there is any similar command on other Unix env

Answer 1

On Linux, with bash, to output as quoted args so you can edit the command and rerun it

On Solaris, with bash (tested with 3.2.51(1)-release) and without gnu userland:

IFS=$'\002' tmpargs=( $( pargs "${pid}" \
    | /usr/bin/sed -n 's/^argv\[[0-9]\{1,\}\]: //gp' \
    | tr '\n' '\002' ) )
for tmparg in "${tmpargs[@]}"; do
    printf "%q " "$( echo -e "${tmparg}" )"
done; echo

Linux bash Example (paste in terminal):

{
## setup intial args
argv=( /bin/bash -c '{ /usr/bin/sleep 10; echo; }' /dev/null 'BEGIN {system("sleep 2")}' "this is" \
    "some" "args "$'\n'" that" $'\000' $'\002' "need" "quot"$'\t'"ing" )

## run in background
"${argv[@]}" &

## recover into eval string that assigns it to argv_recovered
eval_me=$(
    printf "argv_recovered=( "
    

Output:

MATCH

Solaris Bash Example:

{
## setup intial args
argv=( /bin/bash -c '{ /usr/bin/sleep 10; echo; }' /dev/null 'BEGIN {system("sleep 2")}' "this is" \
    "some" "args "$'\n'" that" $'\000' $'\002' "need" "quot"$'\t'"ing" )

## run in background
"${argv[@]}" &
pargs "${!}"
ps -fp "${!}"

declare -p tmpargs
eval_me=$(
    printf "argv_recovered=( "
    IFS=$'\002' tmpargs=( $( pargs "${!}" \
        | /usr/bin/sed -n 's/^argv\[[0-9]\{1,\}\]: //gp' \
        | tr '\n' '\002' ) )
    for tmparg in "${tmpargs[@]}"; do
        printf "%q " "$( echo -e "${tmparg}" )"
    done; echo
    printf " )\n"
)

## do eval
eval "${eval_me}"


## verify match
if [ "$( declare -p argv )" == "$( declare -p argv_recovered | sed 's/argv_recovered/argv/' )" ];
then
    echo MATCH
else
    echo NO MATCH
fi
}

Output:

MATCH