How to view the output of a running process in another bash session? - Unix & Linux Stack Exchange

How to view the output of a running process in another bash session?

capture pts output

ps -ef |grep sshd

grep whatever process you want to attach

strace -e write=1,2 -e trace=write -p xxxx

Here is more complete example:

strace -e trace=write -s1000 -fp 18386 2>&1 \
| grep --line-buffered -o '".\+[^"]"' \
| grep --line-buffered -o '[^"]\+[^"]' \
| while read -r line; do
  printf "%b" $line;
done

To avoid that, lets simplify the whole process, so lets define the following formatter alias:
alias format-strace='grep --line-buffered -o '\''".\+[^"]"'\'' | grep --line-buffered -o '\''[^"]*[^"]'\'' | while read -r line; do printf "%b" $line; done | tr "\r\n" "\275\276" | tr -d "[:cntrl:]" | tr "\275\276" "\r\n"'

where:

grep -o '".\+[^"]"' - select double-quoted string with quotes
grep -o '[^"]*[^"]' - select text within the double quotes
while read -r line - store each line into $line and do some action (help read)
printf "%b" $line - print line by expanding backslash escape sequences
tr "\r\n" "\275\276" - temporarily replace \r\n into \200\201
tr -d "[:cntrl:]" - remove all control characters
tr "\275\276" "\r\n" - restore new line endings


then the complete example to trace some command (e.g. php) can look like:
strace -e trace=read,write,recvfrom,sendto -s 1000 -fp $(pgrep -n php) 2>&1 | format-strace