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Parsing a control file loop

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# 8  
Old 05-14-2018
Enclose the $line in double quote to have the shell preserve spaces within.

But, I may be thick-witted, but the entire problem escapes me, even with the new sample.
OK, you have the OS - however determined - in the first field. What is the second field for? And, why not just list the commands to be executed in a list right after the OS paragraph header?

Please give some consistent context / background to help people understand what you're after. The HP-UX problem from post#1 seems to have disappeared in the new sample?
This User Gave Thanks to RudiC For This Post:
The Gamemaster
# 9  
Old 05-14-2018
Quote:
Originally Posted by RudiC
Enclose the $line in double quote to have the shell preserve spaces within.

But, I may be thick-witted, but the entire problem escapes me, even with the new sample.
OK, you have the OS - however determined - in the first field. What is the second field for? And, why not just list the commands to be executed in a list right after the OS paragraph header?

Please give some consistent context / background to help people understand what you're after. The HP-UX problem from post#1 seems to have disappeared in the new sample?
The script is for modifying a specific configuration file (ps_mon.cfg) on different servers. The 2nd field is there, so that the script will search for that keyword first in the config file, and if there's an *ACTION already added in the next line after that keyword, will not proceed on executing the command in the 3rd field. Otherwise, the script will execute the command to insert that *ACTION line after the keyword. Obviously, I have those sorted in, though I'm open to suggestions if you have simpler code since I'm a clunky coder.

Once the script got the OS of the server it will execute on, for example RHEL, how can I get only the lines with RHEL, then assign the second field to $PROCESS and the third field to $COMMAND in a loop, so that I can accomplish the above?
# 10  
Old 05-14-2018
One comment:
assuming there is embedded sed code, then
Code:
 's/^syslogd.*$/&\n*ACTION \/etc\/init.d\/syslog start/'

substitutes the current line by itself plus a new line.
This is the same as appending a new line, and the a command does it nicely
Code:
 '/^syslogd/ a*ACTION /etc/init.d/syslog start'

And no backslashes needed!
This User Gave Thanks to MadeInGermany For This Post:
The Gamemaster
# 11  
Old 05-14-2018
The following file has another separator at the end of the command field
Code:
RHEL:syslogd:sed -i '/^syslogd/ a*ACTION /etc/init.d/syslog start/' $CFG_DIR/ps_mon.cfg:
RHEL:ntpd:"sed -i '/^ntpd/ a*ACTION \/etc\/init.d\/ntpd start/' $CFG_DIR/ps_mon.cfg:
RHEL:scopeux:"sed -i '/^scopeux/ a*ACTION /opt/perf/bin/ovpa start all/' $CFG_DIR/ps_mon.cfg:

SUSE:cron:"sed -i '/^cron/ a*ACTION /etc/init.d/cron start/' $CFG_DIR/ps_mon.cfg:
SUSE:scopeux:"sed -i '/^scopeux/ a*ACTION /opt/perf/bin/ovpa start all/' $CFG_DIR/ps_mon.cfg:
SUSE:midaemon:"sed -i '/^midaemon/ a*ACTION /opt/perf/bin/ovpa start all/' $CFG_DIR/ps_mon.cfg:

HP-UX:scopeux:file=$CFG_DIR/ps_mon.cfg; sed 's/^scopeux/ a\
*ACTION /opt/perf/bin/ovpa start all' "$file" > "$file".tmp && mv "$file".tmp "$file":
HP-UX:midaemon:file=$CFG_DIR/ps_mon.cfg; sed '/^midaemon/ a\
*ACTION /opt/perf/bin/ovpa start all' "$file" > "$file".tmp && mv "$file".tmp "$file":
HP-UX:perfalarm:file=$CFG_DIR/ps_mon.cfg; sed '/^perfalarm/ a\
*ACTION /opt/perf/bin/ovpa start all' "$file" > "$file".tmp && mv "$file".tmp "$file":

It can be parsed by the following Bourne-compatible shell script
Code:
#!/bin/sh
PATH=/bin:/usr/bin
sep=":"
while IFS=$sep read -r f1 f2 f3
do
  [ -n "$f1" ] || continue
  cmd=$f3
  while
    case $cmd in
    (*$sep) break;;
    esac
  do
    read line
    cmd="$cmd
$line"
  done
  cmd=`expr X"$cmd" : X"\(.*\)$sep"` 
  echo "\
field1 = $f1
field2 = $f2 
cmd = $cmd"
done

The good thing is, the command can contain any characters: \n or newlines, and all quoting characters, and even the : character!
NB the shell script reads from stdin. Run it with /bin/sh /path/to/script < input_file.
Last edited by MadeInGermany; 05-14-2018 at 02:43 PM..
This User Gave Thanks to MadeInGermany For This Post:
The Gamemaster
# 12  
Old 05-22-2018
Quote:
Originally Posted by MadeInGermany
The following file has another separator at the end of the command field
Code:
RHEL:syslogd:sed -i '/^syslogd/ a*ACTION /etc/init.d/syslog start/' $CFG_DIR/ps_mon.cfg:
RHEL:ntpd:"sed -i '/^ntpd/ a*ACTION \/etc\/init.d\/ntpd start/' $CFG_DIR/ps_mon.cfg:
RHEL:scopeux:"sed -i '/^scopeux/ a*ACTION /opt/perf/bin/ovpa start all/' $CFG_DIR/ps_mon.cfg:

SUSE:cron:"sed -i '/^cron/ a*ACTION /etc/init.d/cron start/' $CFG_DIR/ps_mon.cfg:
SUSE:scopeux:"sed -i '/^scopeux/ a*ACTION /opt/perf/bin/ovpa start all/' $CFG_DIR/ps_mon.cfg:
SUSE:midaemon:"sed -i '/^midaemon/ a*ACTION /opt/perf/bin/ovpa start all/' $CFG_DIR/ps_mon.cfg:

HP-UX:scopeux:file=$CFG_DIR/ps_mon.cfg; sed 's/^scopeux/ a\
*ACTION /opt/perf/bin/ovpa start all' "$file" > "$file".tmp && mv "$file".tmp "$file":
HP-UX:midaemon:file=$CFG_DIR/ps_mon.cfg; sed '/^midaemon/ a\
*ACTION /opt/perf/bin/ovpa start all' "$file" > "$file".tmp && mv "$file".tmp "$file":
HP-UX:perfalarm:file=$CFG_DIR/ps_mon.cfg; sed '/^perfalarm/ a\
*ACTION /opt/perf/bin/ovpa start all' "$file" > "$file".tmp && mv "$file".tmp "$file":

It can be parsed by the following Bourne-compatible shell script
Code:
#!/bin/sh
PATH=/bin:/usr/bin
sep=":"
while IFS=$sep read -r f1 f2 f3
do
  [ -n "$f1" ] || continue
  cmd=$f3
  while
    case $cmd in
    (*$sep) break;;
    esac
  do
    read line
    cmd="$cmd
$line"
  done
  cmd=`expr X"$cmd" : X"\(.*\)$sep"` 
  echo "\
field1 = $f1
field2 = $f2 
cmd = $cmd"
done

The good thing is, the command can contain any characters: \n or newlines, and all quoting characters, and even the : character!
NB the shell script reads from stdin. Run it with /bin/sh /path/to/script < input_file.
Thank you very much for this input. I apologize if I wasn't able to reply in the past few days. I got sick.

I haven't tested it yet, but will do today and let you know how it goes.

---------- Post updated at 11:00 AM ---------- Previous update was at 10:33 AM ----------

Ok tested the code at last, and while the parsing works pretty well, the variable $CFG_DIR is taken literally and I can't substitute any value for it. So when I try to execute the $cmd, I get the error "$CFG_DIR/ps_mon.cfg not found".

This is the only problem I have left, and once it's solved then I can finish the script.
Last edited by The Gamemaster; 05-22-2018 at 12:00 AM..
# 13  
Old 05-22-2018
Quote:
Originally Posted by The Gamemaster
Ok tested the code at last, and while the parsing works pretty well, the variable $CFG_DIR is taken literally and I can't substitute any value for it. So when I try to execute the $cmd, I get the error "$CFG_DIR/ps_mon.cfg not found".
For this kind of situations there is the eval keyword. Its use is always the last resort, so this is not a "recommendation" and the advice is to handle it with extreme care.

Since you don't show us your code you will have to find out how to incorporate it yourself. Just so much: basically it starts the parsing of the command line a second time. Here is an example what that means:

Code:
var="abc"
abc="123"
print - $$var

Now, this will NOT work. One might expect that "$var" is expanded to "abc" and "$abc" is expanded to "123", but this is not the case. In fact all variables are expanded at the same time and once they are - they are. There is no going back and expanding a second time.

In comes eval. This indeed starts the whole parsing process a second time and hence:

Code:
var="abc"
abc="123"
eval print - \$$var

will do the second indirection. This now works exactly like described above. Notice that the first "$" had to be escaped to protect it from being interpreted in the first parsing pass.

I hope this helps.

bakunin
This User Gave Thanks to bakunin For This Post:
The Gamemaster
# 14  
Old 05-22-2018
Quote:
Originally Posted by bakunin
For this kind of situations there is the eval keyword. Its use is always the last resort, so this is not a "recommendation" and the advice is to handle it with extreme care.

Since you don't show us your code you will have to find out how to incorporate it yourself. Just so much: basically it starts the parsing of the command line a second time. Here is an example what that means:

Code:
var="abc"
abc="123"
print - $$var

Now, this will NOT work. One might expect that "$var" is expanded to "abc" and "$abc" is expanded to "123", but this is not the case. In fact all variables are expanded at the same time and once they are - they are. There is no going back and expanding a second time.

In comes eval. This indeed starts the whole parsing process a second time and hence:

Code:
var="abc"
abc="123"
eval print - \$$var

will do the second indirection. This now works exactly like described above. Notice that the first "$" had to be escaped to protect it from being interpreted in the first parsing pass.

I hope this helps.

bakunin
This basically solved it. Thanks so much for everyone's help here.
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