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', what field delimiter I should say?
$ps axu | grep jboss
jboss 2574 0.0 0.0 3744 1092 ? S Aug17 0:00 /bin/sh /usr/java/jboss/bin/run.sh -c example.com -b 0.0.0.0
cut -d' '
is not what I want, for it's only for one single space.
awk
is not what I am looking for either, but how to do with 'cut'?
thanks.
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
And even shorter (not using cut at all) is:
pgrep jboss
Personally, I tend to use awk for jobs like this. For example:
ps axu| grep jboss | grep -v grep | awk '{print $5}'
awk
version is probably the best way to go, but you can also use cut
if you firstly squeeze the repeats with tr
:
ps axu | grep jbos[s] | tr -s ' ' | cut -d' ' -f5
# ^^^^^^^^^^^^ ^^^^^^^^^ ^^^^^^^^^^^^^
# | | |
# | | get 5th field
# | |
# | squeeze spaces
# |
# avoid grep itself to appear in the list
I am going to nominate tr -s [:blank:]
as the best answer.
Why do we want to use cut? It has the magic command that says "we want the third field and every field after it, omitting the first two fields"
cat log | tr -s [:blank:] |cut -d' ' -f 3-
I do not believe there is an equivalent command for awk or perl split where we do not know how many fields there will be, ie out put the 3rd field through field X.
I like to use the tr -s command for this
ps aux | tr -s [:blank:] | cut -d' ' -f3
This squeezes all white spaces down to 1 space. This way telling cut to use a space as a delimiter is honored as expected.
Another way if you must use cut command
ps axu | grep [j]boss |awk '$1=$1'|cut -d' ' -f5
In Solaris, replace awk with nawk
or /usr/xpg4/bin/awk
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]'
One way around this is to go:
$ps axu | grep jboss | sed 's/\s\+/ /g' | cut -d' ' -f3
to replace multiple consecutive spaces with a single one.
My approach is to store the PID to a file in /tmp, and to find the right process using the -S
option for ssh
. That might be a misuse but works for me.
#!/bin/bash
TARGET_REDIS=${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.
If you want to pick columns from a ps output, any reason to not use -o?
e.g.
ps ax -o pid,vsz
ps ax -o pid,cmd
Minimum column width allocated, no padding, only single space field separator.
ps ax --no-headers -o pid:1,vsz:1,cmd
3443 24600 -bash
8419 0 [xfsalloc]
8420 0 [xfs_mru_cache]
8602 489316 /usr/sbin/apache2 -k start
12821 497240 /usr/sbin/apache2 -k start
12824 497132 /usr/sbin/apache2 -k start
Pid and vsz given 10 char width, 1 space field separator.
ps ax --no-headers -o pid:10,vsz:10,cmd
3443 24600 -bash
8419 0 [xfsalloc]
8420 0 [xfs_mru_cache]
8602 489316 /usr/sbin/apache2 -k start
12821 497240 /usr/sbin/apache2 -k start
12824 497132 /usr/sbin/apache2 -k start
Used in a script:-
oldpid=12824
echo "PID: ${oldpid}"
echo "Command: $(ps -ho cmd ${oldpid})"
I still like the way Perl handles fields with white space.
First field is $F[0].
$ ps axu | grep dbus | perl -lane 'print $F[4]'
Source: Stackoverflow.com