I need help with breaking down this script command by command on whatn it supposen to do!!

[michealbantor]

michealbantor (TechnicalUser)
(OP)
26 May 18 00:46
[# command for gathering Listener Log

set v_listener_command "; echo ' Listener Log' | tr '\\n' ':'; echo '' | tr '\\n' ' ' ; lsnrctl status | grep Log | awk '{ print \$4 }' | sed 's/alert\\/log.xml/trace\\/listener.log/g' | tr '\\n' ' '; echo '-' | tr '\\n' ' ' ; du -sk `lsnrctl status | grep Log | awk '{ print \$4 }' | sed 's/alert\\/log.xml/trace\\/listener.log/g'` | awk '{ print \$1 }' | tr '\\n' ' ' ; echo '(KB)'"]

 

[ChrisHirst]

what it is supposed to do is relatively easy

it sets an environment variable "v_listener_command" to a value determined from a sequence of shell commands.

Breakdown:
a ; (semicolon) separates commands on a single line
s | (called a pipe) passes the result from the first command to the following 'piped' command

so;

 echo ' Listener Log' | tr '\\n' ':';

outputs a string and 'pipes' it to a tr command

 tr '\\n' ':'

tr is a 'translate' statement which replaces characters in a string.

your example replaces a newline character (\n) with a colon.

use

man 1 tr

in a shell window for more on tr.

lsnrctl status

Oracle database listener status request but not my department a I don't use Oracle. but the output is piped to grep for lines the word 'Log' then passes that to awk to get the 4th word/column of those lines.

Eg echo 'This is a test' | awk '{ print \$4 }' will return 'test'

[more to follow]

Chris.

Indifference will be the downfall of mankind, but who cares?
Time flies like an arrow, however, fruit flies like a banana.

Never mind this jesus character, stars had to die for me to live.

 

[ChrisHirst]

Meanwhile, back at the ranch;

 | sed 's/alert\\/log.xml/trace\\/listener.log/g'

sed .. is the UNIX/Linux Stream Editor, used for replacing, deleting, editing or inserting text in a text data stream or in files.

your example replaces all instances (the /g means global) of 'alert/log.xml' with 'trace/listener.log'

 man sed

for the manual pages.

Chris.

Indifference will be the downfall of mankind, but who cares?
Time flies like an arrow, however, fruit flies like a banana.

Never mind this jesus character, stars had to die for me to live.

 

[michealbantor]

You breakdown is much appreciated....thank you very much for your contribution.