PID length

Shell Programming and Scripting
1

Does somebody know how many characters can have a PID as maximum?

I'm trying to get the PID of another process running in the same machine. I'm doing this:

ps -ef | grep "bin/Alime" | grep -v grep  | cut -c10-16

but I don't know if I 'll have enough with six chars. Which is the max value that it can take?

thanks in advance

2

that depends on the maximum number allowed for a PID and it varies from system to system

3

I'm looking for a PIDMAX or something like this, but I can't find anything. This is my system:

ASASTR:include> uname -a
OSF1 CLHASASTR V5.1 2650 alpha

Thanks again

4

cannot you just get the whole column instead of relying on character ranges?
something like:

ps -ef | grep 'in/Alime' | cut -d ' ' -f1
5

yes, the whole column would be great. I have tried to get only the second column

 ps -ef | grep "bin/Alime" | grep -v grep  | cut -f 2

but it shows the whole line again. I don't know why, maybe the command is not correct.

thanks

6 
ps -ef | grep 'in/Alime' | cut -d ' ' -f 2

cut's field delimiter is 'tab' by default......

7

these are my outputs:

ASASTR:clh> ps -ef | grep "bin/Alime" | grep -v grep
clh      221867 217065  0.0 11:34:01 pts/4        0:00.08 /usr/local/clh/ALPHA/oasys/bin/AlimentaLookAhead

ASASTR:clh> ps -ef | grep "bin/Alime" | grep -v grep  | cut -c10-16
221867

ASASTR:clh> ps -ef | grep "bin/Alime" | grep -v grep  | cut -d ' ' -f1
clh

ASASTR:clh>  ps -ef | grep "bin/Alime" | grep -v grep  | cut -d ' ' -f2

ASASTR:clh>  ps -ef | grep "bin/Alime" | grep -v grep  | cut -f2
clh      221867 217065  0.0 11:34:01 pts/4        0:00.08 /usr/local/clh/ALPHA/oasys/bin/AlimentaLookAhead

asking for the first column (-f1) i get the username, but asking for the second (-f2) i get the whole line.
Thanks.

8 
ps -ef | grep "bin/Alime" | grep -v grep | awk '{print $2}'
9

check this link

10 
ps -ef | awk '/bin\/Alime/{print $2}'
11

yep, no need to all the greppin' brouhaha

12

I have found this PID_MAX:

(./usr/sys/include/sys/limits.h)

#define PID_MAX              INT_MAX         /* max value for process ID */

and INT_MAX is defined as:
(./arch/alpha/machlimits.h)

#define       INT_MAX          2147483647     /* max value for an int */

2147483647 --> 10 characters

Thank you very much to all of you for your time

Oops ! The awk option is much better ! thanks again !!

13

ps -ef | grep your_process | grep -v grep | tr -s " " | cut -f2

14

probably doesn't matter. to reduce redundant use of grep -v grep, you could use awk

ps -ef | awk '/process/{print $2}'
15

:cool: Ghostdog , that was a good piece, But at times feel I can type "grep -v grep " much faster than trying to escape the /'s when using awk.

for an example , to grep the '/etc/init' , I feel that the second way is pretty easier and faster to type

 UID   PID  PPID   C    STIME    TTY  TIME CMD
root     1     0   0   Jan 14      - 40:54 /etc/init

team$ ps -ef | awk '/\/etc\/init/ { print $0 }'
root 1 0 0 Jan 14 - 40:53 /etc/init
team$

team$ ps -ef | grep '/etc/init' | grep -v grep
root 1 0 0 Jan 14 - 40:55 /etc/init
team$