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Category:TXR: Difference between revisions
→Simple Query: Extremely simple query.
(Ported to Windows natively.) |
(→Simple Query: Extremely simple query.) |
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The success of a directive means that computation proceeds to the next directive (and, if this is a pattern match, the input position advances). Failure means that the enclosing query fails, triggering back-tracking behaviors and possibly failure of the entire query.
==Extremely Simple Query==
Extract first matching line from the password file. Of course, TXR matches are not restricted to single line!
<lang bash>$ txr -c '@(skip)
@user:@pw:@uid:@gid:@gecos:@home:@shell' /etc/passwd</lang>
<pre>
user="root"
pw="x"
uid="0"
gid="0"
gecos="root"
home="/root"
shell="/bin/bash"</pre>
Now, pre-bind the <code>user</code> variable first to retrieve some other user. Now <code>@(skip)</code> kicks into action, skipping non-matching material:
<lang bash>$ txr -Duser=sshd -c '@(skip)
@user:@pw:@uid:@gid:@gecos:@home:@shell' /etc/passwd</lang>
<pre>user="sshd"
pw="x"
uid="114"
gid="65534"
gecos=""
home="/var/run/sshd"
shell="/usr/sbin/nologin"</pre>
==Simple Query==
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