sap*preconfigure: sysctl checks fail when config file has comments

[rob0d]

Hi @berndfinger,

PR#807 introduced checks of kernel parameters to support indepotency.
However, under very rare circumstances when the sysctl conf files contain comments (#) this check fails as the awk command includes the line with the comments as a kernel parameter to check.
It generates something like:
sysctl #This is comment net.ipv4.tcp_rmem

This PR makes a minor change to make awk exclude all lines starting with # (i.e. ^#).

Kudos @James-Allen_nbs.

[berndfinger]

@rob0d Thanks for this. I had a quick look at man sysctl.d (RHEL 9) and it mentions that empty lines and those whose first non-whitespace character is "#" or ";" are ignored.

The following example should contain any allowed patterns I can think of (note that the second empty line contains three spaces and that the third empty line contained a tab character, and that the lines with a comment sign at column 8 were starting with a tab character):

net.ipv4.tcp_max_syn_backlog=8192
net.ipv4.tcp_timestamps=1

   
        
net.ipv4.tcp_slow_start_after_idle=0
net.core.wmem_max=4194304
#net.core.wmem_max=4194304
# net.core.wmem_max=4194304
 # net.core.wmem_max=4194304
        # net.core.wmem_max=4194304
;net.core.wmem_max=4194304
; net.core.wmem_max=4194304
 ; net.core.wmem_max=4194304
        ; net.core.wmem_max=4194304
net.core.rmem_max=6291456

It seems that the following awk statement will display only valid parameters:

awk 'BEGIN{FS="="; printf ("sysctl ")}NF>1&&!/^\s*[#;]/{printf ("%s ", $1)}' FILE

Note: NF is 0 for a line without a white space and 1 for a line with one or more white space characters.

[rob0d]

@berndfinger oh yes. We rushed a fix out as we needed to continue, but this is definitely better. Updated. Thanks Bernd.

[berndfinger]

LGTM!