Re: "echo"ing a psql command in a bash script

* Jim Wilson <jimw(at)kelcomaine(dot)com> [030904, 14:39]:
> Ennio-Sr said:
>
> > (once for all):
> > cmnd=echo psql mydb -x -c "SELECT * FROM tb_nm WHERE $col_nm LIKE '%$k_r%'"
>
> That will be executed immediately, and give you an error.

In fact, yes, you're right! it gives <ERROR: parser: parse error at or
near "'" > ...but after the second Enter, shows the result.
....
>
> > (in each <case n>):
> > col_nm="....."
> > echo $cmnd
>
> I'm surprised you get anything. AFAIK this should parse the files in your
> directory into column names. Maybe you are doing something slightly different?

Oops: the show repetition after exiting (q) psql was due to a 'normal'
psql select left over between the lines of my script. Sorry for that,
althoug it helped me learn something new ... :-)

>
> Rather than setting the $cmnd variable, try using something like this:
>
> echo mydb -x -c \"SELECT "*" FROM tb_nm WHERE $col_nm LIKE \'%$k_r%\'\" |
> xargs psql

This works, but the pager doesn't! Whereas my former cmnd= .... seems to
work better, although I had to re-site it [See my script below ...]
>
> I'm not sure where you are storing your column names,

I'm not sure how to interpret that: if you refer to the various $col_nm
only one per case is involved and chosen for each case [see below]

> but if you can pipe it
> as a list into the above you won't need to rum a loop in your script. There
> are a thousand ways to do this, but most important is remember to quote the
> "*" so the shell doesn't parse it. BTW You did not say, so I'm also assuming
> you are using "bash" or "sh" since that's what this looks like. :-)

This is again my fault! I'm using bash script, under Debian/Woody k
2.2.22 and PostgreSQL 7.2.1

And this is an extract from my script:

-------------------------- quote -------------------------

#!/bin/sh
bold=`tput smso`
offbold=`tput rmso`
clear
while test 1 -gt 0; do

echo ""
echo "$bold SCEGLI IL CAMPO SU CUI EFFETTUARE LA RICERCA $offbold"
## I (Choose the field to search on)
echo ""
echo " 0 - n_prog | 14 - car_tec_ed"
[ ..... ]
echo " 13 - n_pag_testo | 27 - dummy"

echo " "
echo "$bold (Per uscire premere Enter) $offbold"
echo ""
echo " Inserire il numero corrispondente al programma desiderato: "
##
read key

# ++++
# MY FIRST ATTEMPT :
#--->cmnd=echo psql mydb -x -a -c "select * from bib_lt where $k_c like '%$k_r%'"
# Does not perform well: gives parsing error etc ....

# ++++

case "$key" in
"")
exit 1
;;

0)

[... cut ...]

# THIS IS AN EXAMPLE OF WHAT GOES ON IN EACH OF THE 27 CASES:
4)
echo " Search by author "
echo " ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^"
echo " Input author's name: " ; read k_r
psql mydb -x -c "select * from bib_lt where autore like\
upper('%$k_r%')"
;;

[... cut ...]

# HERE I TESTED THE NEW WAY OF DOING IT:

7)
echo " Search by publishers "
echo " ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^"
echo " Inserire l'editore da ricercare: " ; read k_r
### psql mydb -x -a -c "select * from bib_lt where editore like '%$k_r%'"

k_c="editore"
echo $cmnd ## <---

;;

[ ... cut ...]
27)
echo " Ricerca per dummy (R/"") "
echo " ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^"
echo " Inserire l'argomento da ricercare: " ; read k_r
psql mydb -x-a-c "select * from bib_lt where dummy like '%$k_r%'"
;;

qQ)
exit 1 # esci dal loop
;;

esac

### THIS IS THE CORRECT SITE WHERE TO PUT IT!
---------------------------------------------
#echo mydb -x -c \"select "*" from bib_lt where $k_c like \'%$k_r%\'\"
#| xargs psql # suggested by Jim Wilson -> OK, works but scrolls
# ---> endlessly (pager doesn't work!) <---

# This also works (either with "*" or as follows):
cmnd=echo psql mydb -x -c "select * from bib_lt where $k_c like '%$k_r%'"
# and, what's more, the pager goes fine!

done

------------------------------ unquote ---------------------------------

As you can see, placing the cmnd definition at the end of the loop gives
a correct result: I would never have thought it was possible to do that,
as the token '$cmnd' is called (within the loop) before its definition
has been given. But that's it| ... :-)

BTW, can you suggest any particular reading about psql commands and how
they interact with bash scripts? I was unable to find anything on pg
docs, including B.Momjan book, and on Rute's Advanced Scripting.
One of the issues I could not solve was : How can I put two psql
commands on the same script line?

Anyway, thank you very much for your attention, Jim.
All the best,
Ennio

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