Editing ANSI escape code (section)

=== In shell scripting ===

ANSI escape codes are often used in [[UNIX]] and UNIX-like [[virtual console|terminals]] to provide [[syntax highlighting]]. For example, on compatible terminals, the following ''[[ls|list]]'' command color-codes file and directory names by type.

 ls --color

Users can employ escape codes in their scripts by including them as part of ''[[standard output]]'' or ''[[stderr|standard error]]''. For example, the following GNU ''[[sed]]'' command embellishes the output of the ''[[make (software)|make]]'' command by displaying lines containing words starting with "WARN" in [[reverse video]] and words starting with "ERR" in bright yellow on a dark red background ([[letter case]] is ignored). The representations of the codes are highlighted.<ref>{{cite web |url=http://www.debian.org/doc/manuals/debian-reference/ch09.en.html#_colorized_shell_echo |title=Chapter 9. System tips|work=debian.org}}</ref>

 <span style="white-space:pre-wrap;">make 2&gt;&amp;1 | sed -e 's/.*\bWARN.*/<span style="border:1px solid grey;border-radius:5px;color:white;background:black;font-weight:bolder;">\x1b[7m</span>&<span style="border:1px solid grey;border-radius:5px;">\x1b[0m</span>/i' -e 's/.*\bERR.*/<span style="border:1px solid grey;border-radius:5px;color:yellow;background:maroon;font-weight:bolder;">\x1b[93;41m</span>&<span style="border:1px solid grey;border-radius:5px;">\x1b[0m</span>/i'</span>

The following [[Bash (Unix shell)|Bash]] function flashes the terminal (by alternately sending reverse and normal video mode codes) until the user presses a key.<ref>{{cite web |title=VT100.net: Digital VT100 User Guide |url=http://vt100.net/docs/vt100-ug/chapter3.html |access-date=2015-01-19}}</ref>

 flasher () { while true; do printf <span style="border:1px solid grey;border-radius:5px;color:white;background:black;font-weight:bolder;">\\e[?5h</span>; sleep 0.1; printf <span style="border:1px solid grey;border-radius:5px;font-weight:bolder;">\\e[?5l</span>; read -s -n1 -t1 && break; done; }

This can be used to alert a programmer when a lengthy command terminates, such as with {{code|make ; flasher}}{{thin space}}.<ref>{{cite web |title=bash – How to get a notification when my commands are done – Ask Different |url=http://apple.stackexchange.com/questions/9412/how-to-get-a-notification-when-my-commands-are-done |access-date=2015-01-19}}</ref>

 printf \\033c

This will reset the console, similar to the command {{code|reset}} on modern Linux systems; however it should work even on older Linux systems and on other (non-Linux) UNIX variants.