[2024-feb-29] Sad news: Eric Layton aka Nocturnal Slacker aka vtel57 passed away on Feb 26th, shortly after hospitalization. He was one of our Wiki's most prominent admins. He will be missed.
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howtos:general_admin:cli_constructs_and_useful_info [2012/10/20 15:35 (UTC)] – [Quoting] htexmexh | howtos:general_admin:cli_constructs_and_useful_info [2012/12/24 12:08 (UTC)] – [Regex] hazel | ||
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Line 78: | Line 78: | ||
</ | </ | ||
Note that there are no quotes around '' | Note that there are no quotes around '' | ||
+ | == External Links === | ||
+ | * http:// | ||
==== Quoting ==== | ==== Quoting ==== | ||
Quoting may seem complicated, | Quoting may seem complicated, | ||
Line 95: | Line 97: | ||
bash-4.2$ | bash-4.2$ | ||
</ | </ | ||
- | Clearly you need to quote a file with spaces. You could use single quotes here, because no variable | + | Clearly you need to quote a file with spaces. You could use single quotes here, because no variables |
<code bash> | <code bash> | ||
bash-4.2$ for i in $(seq 1 10); do printf "$i "; done; echo; | bash-4.2$ for i in $(seq 1 10); do printf "$i "; done; echo; | ||
Line 144: | Line 146: | ||
</ | </ | ||
Here the shell expands '' | Here the shell expands '' | ||
- | ==== Regex ==== | + | === External Links === |
- | Remember to escape the '' | + | * http:// |
+ | ==== Regular expressions | ||
+ | === Basic === | ||
+ | * '' | ||
+ | * '' | ||
+ | < | ||
< | < | ||
bash-4.2$ cat test.txt | bash-4.2$ cat test.txt | ||
Line 156: | Line 163: | ||
testtxt | testtxt | ||
test | test | ||
+ | </ | ||
+ | * '' | ||
+ | * '' | ||
+ | * '' | ||
+ | * '' | ||
+ | * '' | ||
+ | * '' | ||
+ | * '' | ||
+ | * '' | ||
+ | * Example: '' | ||
+ | * '' | ||
+ | === Extended === | ||
+ | The following must be supported by the program for them to work. For example for grep you must run '' | ||
+ | * '' | ||
+ | * ''?'' | ||
+ | * '' | ||
+ | * '' | ||
+ | * '' | ||
+ | * '' | ||
+ | * '' | ||
+ | * '' | ||
+ | === External Links === | ||
+ | * http:// | ||
+ | * http:// | ||
+ | ==== Useful commands and info ==== | ||
+ | === stat === | ||
+ | Stat is the most accurate way to determine: | ||
+ | * File size in bytes: <code bash> | ||
+ | * File permissions in octal: <code bash> | ||
+ | === awk variable defaults === | ||
+ | An important point is that awk variables are set to zero by default. This may cause problems in some situtations. Example: | ||
+ | <code bash> | ||
+ | echo -ne ' | ||
+ | </ | ||
+ | This works properly because max is set to an empty string and thus has a lower value than any number. Try removing the BEGIN clause and see what happens. Also note that adding '' | ||
+ | === no data directory test === | ||
+ | You can use this to test if a directory contains no data. For example, it will say '' | ||
+ | <code bash> | ||
+ | du -s directory | ||
+ | </ | ||
+ | === cmp === | ||
+ | This can compare two files byte by byte, and can be more useful that checksums. For example, after you burn a CD/DVD, you can run: | ||
+ | <code bash> | ||
+ | cmp slackware.iso /dev/sr0 | ||
+ | </ | ||
+ | It should say the following if the disk burned correctly: | ||
+ | <code bash> | ||
+ | cmp: EOF on slackware.iso | ||
</ | </ | ||
+ | === shell math === | ||
+ | Remember that shell utilities like '' | ||
+ | === shell GUI === | ||
+ | There are numerous programs that allow you to create GUIs from a shell script. | ||
+ | * [[http:// | ||
+ | * [[https:// | ||
+ | * [[http:// | ||
+ | === External Links === | ||
+ | * [[http:// | ||
+ | * [[http:// | ||
+ | * [[http:// | ||
+ | * [[http:// | ||
====== Sources ====== | ====== Sources ====== | ||
<!-- If you are copying information from another source, then specify that source --> | <!-- If you are copying information from another source, then specify that source --> | ||
Line 164: | Line 230: | ||
<!-- * Originally written by [[wiki: | <!-- * Originally written by [[wiki: | ||
<!-- * Contributions by [[wiki: | <!-- * Contributions by [[wiki: | ||
+ | * I quoted '' | ||
+ | * I used '' | ||
+ | * Written by [[wiki: | ||
<!-- Please do not modify anything below, except adding new tags.--> | <!-- Please do not modify anything below, except adding new tags.--> | ||
<!-- You must remove the tag-word " | <!-- You must remove the tag-word " | ||
- | {{tag> | + | {{tag> |