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1 <stránka |
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2 xmlns="https://trac.frantovo.cz/xml-web-generator/wiki/xmlns/strana" |
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3 xmlns:m="https://trac.frantovo.cz/xml-web-generator/wiki/xmlns/makro"> |
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4 |
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5 <nadpis>Filtering /etc/fstab using relpipe-tr-grep</nadpis> |
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6 <perex>list only records with desired filesystem types</perex> |
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7 <m:pořadí-příkladu>00900</m:pořadí-příkladu> |
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8 |
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9 <text xmlns="http://www.w3.org/1999/xhtml"> |
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10 |
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11 <p> |
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12 If we are interested only in certain records in some relation, we can filter it using <code>relpipe-tr-grep</code>. |
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13 If we want to list e.g. only Btrfs and XFS file systems from our <code>fstab</code> (see above), we will run: |
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14 </p> |
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15 |
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16 |
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17 <m:pre jazyk="bash"><![CDATA[relpipe-in-fstab | relpipe-tr-grep 'fstab' 'type' 'btrfs|xfs' | relpipe-out-tabular]]></m:pre> |
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18 |
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19 <p>and we will get following filtered result:</p> |
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20 <pre><![CDATA[fstab: |
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21 ╭─────────────────┬──────────────────────────────────────┬──────────────────────┬───────────────┬──────────────────┬────────────────┬────────────────╮ |
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22 │ scheme (string) │ device (string) │ mount_point (string) │ type (string) │ options (string) │ dump (integer) │ pass (integer) │ |
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23 ├─────────────────┼──────────────────────────────────────┼──────────────────────┼───────────────┼──────────────────┼────────────────┼────────────────┤ |
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24 │ UUID │ a2b5f230-a795-4f6f-a39b-9b57686c86d5 │ /home │ btrfs │ relatime │ 0 │ 2 │ |
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25 │ │ /dev/mapper/sdf_crypt │ /mnt/private │ xfs │ relatime │ 0 │ 2 │ |
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26 ╰─────────────────┴──────────────────────────────────────┴──────────────────────┴───────────────┴──────────────────┴────────────────┴────────────────╯ |
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27 Record count: 2]]></pre> |
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28 |
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29 <p> |
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30 Command arguments are similar to <code>relpipe-tr-sed</code>. |
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31 Everything is a regular expression. |
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32 Only relations matching the regex will be filtered, others will flow through the pipeline unmodified. |
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33 If the attribute regex matches more attribute names, filtering will be done with logical OR |
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34 i.e. the record is included if at least one of that attributes matches the search regex. |
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35 </p> |
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36 |
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37 <p> |
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38 If we need exact match of the whole attribute, we have to use something like <code>'^btrfs|xfs$'</code>, |
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39 otherwise mere substring-match is enough to include the record. |
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40 </p> |
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41 |
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42 </text> |
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43 |
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44 </stránka> |