How to specify more spaces for the delimiter using cut?

Question

Is there any way to specify a field delimiter for more spaces with the cut command? (like \" \"+) ? For example: In the following string, I like to reach value \'3744\', wha

Answer 1

As an alternative, there is always perl:

ps aux | perl -lane 'print $F[3]'

Or, if you want to get all fields starting at field #3 (as stated in one of the answers above):

ps aux | perl -lane 'print @F[3 .. scalar @F]'

Answer 2

Personally, I tend to use awk for jobs like this. For example:

ps axu| grep jboss | grep -v grep | awk '{print $5}'

Answer 3

Actually awk is exactly the tool you should be looking into:

ps axu | grep '[j]boss' | awk '{print $5}'

or you can ditch the grep altogether since awk knows about regular expressions:

ps axu | awk '/[j]boss/ {print $5}'

But if, for some bizarre reason, you really can't use awk, there are other simpler things you can do, like collapse all whitespace to a single space first:

ps axu | grep '[j]boss' | sed 's/\s\s*/ /g' | cut -d' ' -f5

---

That grep trick, by the way, is a neat way to only get the jboss processes and not the grep jboss one (ditto for the awk variant as well).

The grep process will have a literal grep [j]boss in its process command so will not be caught by the grep itself, which is looking for the character class [j] followed by boss.

This is a nifty way to avoid the | grep xyz | grep -v grep paradigm that some people use.

Answer 4

Shorter/simpler solution: use cuts (cut on steroids I wrote)

ps axu | grep '[j]boss' | cuts 4

Note that cuts field indexes are zero-based so 5th field is specified as 4

http://arielf.github.io/cuts/

And even shorter (not using cut at all) is:

pgrep jboss

Answer 5

My approach is to store the PID to a file in /tmp, and to find the right process using the -S option for ssh. That might be a misuse but works for me.

#!/bin/bash

TARGET_REDIS=${1:-redis.someserver.com}
PROXY="proxy.somewhere.com"

LOCAL_PORT=${2:-6379}

if [ "$1" == "stop" ] ; then
    kill `cat /tmp/sshTunel${LOCAL_PORT}-pid`
    exit
fi

set -x

ssh -f -i ~/.ssh/aws.pem centos@$PROXY -L $LOCAL_PORT:$TARGET_REDIS:6379 -N -S /tmp/sshTunel$LOCAL_PORT  ## AWS DocService dev, DNS alias
# SSH_PID=$! ## Only works with &
SSH_PID=`ps aux | grep sshTunel${LOCAL_PORT} | grep -v grep | awk '{print $2}'`
echo $SSH_PID > /tmp/sshTunel${LOCAL_PORT}-pid

Better approach might be to query for the SSH_PID right before killing it, since the file might be stale and it would kill a wrong process.

Answer 6

One way around this is to go:

$ps axu | grep jboss | sed 's/\s\+/ /g' | cut -d' ' -f3

to replace multiple consecutive spaces with a single one.