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Support '' for literal ' in psql single-quote strings, documentation update.

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This commit is contained in:
Bruce Momjian
2006-05-31 11:35:17 +00:00
parent eaca1175e9
commit c3c3902611
2 changed files with 9 additions and 6 deletions
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10
doc/src/sgml/ref/psql-ref.sgml
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@ -1,5 +1,5 @@
<!--
$PostgreSQL: pgsql/doc/src/sgml/ref/psql-ref.sgml,v 1.162 2006/05/26 19:51:29 tgl Exp $
$PostgreSQL: pgsql/doc/src/sgml/ref/psql-ref.sgml,v 1.163 2006/05/31 11:35:17 momjian Exp $
PostgreSQL documentation
-->
@ -2262,7 +2262,7 @@ testdb=&gt; <userinput>SELECT * FROM :foo;</userinput>
copy the contents of a file into a table column. First load the file into a
variable and then proceed as above.
<programlisting>
testdb=&gt; <userinput>\set content '\'' `cat my_file.txt` '\''</userinput>
testdb=&gt; <userinput>\set content '''' `cat my_file.txt` ''''</userinput>
testdb=&gt; <userinput>INSERT INTO my_table VALUES (:content);</userinput>
</programlisting>
One possible problem with this approach is that <filename>my_file.txt</filename>
@ -2270,14 +2270,14 @@ testdb=&gt; <userinput>INSERT INTO my_table VALUES (:content);</userinput>
they don't cause a syntax error when the second line is processed. This
could be done with the program <command>sed</command>:
<programlisting>
testdb=&gt; <userinput>\set content '\'' `sed -e "s/'/\\\\\\'/g" &lt; my_file.txt` '\''</userinput>
testdb=&gt; <userinput>\set content '''' `sed -e "s/'/\\\\''/g" &lt; my_file.txt` ''''</userinput>
</programlisting>
Observe the correct number of backslashes (6)! It works
this way: After <application>psql</application> has parsed this
line, it passes <literal>sed -e "s/'/\\\'/g" &lt; my_file.txt</literal>
line, it passes <literal>sed -e "s/'/\\''/g" &lt; my_file.txt</literal>
to the shell. The shell will do its own thing inside the double
quotes and execute <command>sed</command> with the arguments
<literal>-e</literal> and <literal>s/'/\\'/g</literal>. When
<literal>-e</literal> and <literal>s/'/''/g</literal>. When
<command>sed</command> parses this it will replace the two
backslashes with a single one and then do the substitution. Perhaps
at one point you thought it was great that all Unix commands use the