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--- sed:introduction [2020/08/17 10:54] – 192.168.1.1
+++ sed:introduction [2022/06/14 08:20] (current) – [Use of '\t' in sed scripts] peter
@@ Line 12: / Line 12: @@
 ===== Quoting Syntax =====
-The preceding examples use single quotes ('...') instead of double quotes ("...") to enclose editing commands, since sed is typically used on a Unix platform.
+The preceding examples use single quotes **('...')** instead of double quotes **("...")** to enclose editing commands, since sed is typically used on a Unix platform.
-Single quotes prevent the Unix shell from interpreting the dollar sign ($) and back-quotes (`...`), which are expanded by the shell if they are enclosed in double quotes.
+Single quotes prevent the Unix shell from interpreting the dollar sign **($)** and back-quotes **(`...`)**, which are expanded by the shell if they are enclosed in double quotes.
-Users of the "csh" shell and derivatives will also need to quote the exclamation mark (!) with the backslash (i.e., \!) to properly run the examples listed above, even within single quotes.
+Users of the **"csh"** shell and derivatives will also need to quote the exclamation mark **(!)** with the backslash **(i.e., \!)** to properly run the examples listed above, even within single quotes.
-Versions of sed written for DOS invariably require double quotes ("...") instead of single quotes to enclose editing commands.
+Versions of sed written for DOS invariably require double quotes **("...")** instead of single quotes to enclose editing commands.
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@@ Line 28: / Line 28: @@
 However, most versions of sed do not recognize the '\t' abbreviation, so when typing these scripts from the command line, you should press the TAB key instead.
-'\t' is supported as a regular expression metacharacter in awk, perl, and HHsed, sedmod, and GNU sed v3.02.80.
+<WRAP info>
+**NOTE:**  '\t' is supported as a regular expression metacharacter in awk, perl, and HHsed, sedmod, and GNU sed v3.02.80.
+</WRAP>
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@@ Line 43: / Line 46: @@
 sed '/foo/ s//bar/g' filename      # shorthand sed syntax
 </code>
+On line selection or deletion in which you only need to output lines from the first part of the file, a "quit" command (q) in the script will drastically reduce processing time for large files.
+Thus:
+<code bash>
+sed -n '45,50p' filename           # print line nos. 45-50 of a file
+sed -n '51q;45,50p' filename       # same, but executes much faster
+</code>