1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
|
#!/bin/bash
# escaped.sh: escaped characters
#############################################################
### First, let's show some basic escaped-character usage. ###
#############################################################
# Escaping a newline.
# ------------------
echo ""
echo "This will print
as two lines."
# This will print
# as two lines.
echo "This will print \
as one line."
# This will print as one line.
echo; echo
echo "============="
echo "\v\v\v\v" # Prints \v\v\v\v literally.
# Use the -e option with 'echo' to print escaped characters.
echo "============="
echo "VERTICAL TABS"
echo -e "\v\v\v\v" # Prints 4 vertical tabs.
echo "=============="
echo "QUOTATION MARK"
echo -e "\042" # Prints " (quote, octal ASCII character 42).
echo "=============="
# The $'\X' construct makes the -e option unnecessary.
echo; echo "NEWLINE and (maybe) BEEP"
echo $'\n' # Newline.
echo $'\a' # Alert (beep).
# May only flash, not beep, depending on terminal.
# We have seen $'\nnn" string expansion, and now . . .
# =================================================================== #
# Version 2 of Bash introduced the $'\nnn' string expansion construct.
# =================================================================== #
echo "Introducing the \$\' ... \' string-expansion construct . . . "
echo ". . . featuring more quotation marks."
echo $'\t \042 \t' # Quote (") framed by tabs.
# Note that '\nnn' is an octal value.
# It also works with hexadecimal values, in an $'\xhhh' construct.
echo $'\t \x22 \t' # Quote (") framed by tabs.
# Thank you, Greg Keraunen, for pointing this out.
# Earlier Bash versions allowed '\x022'.
echo
# Assigning ASCII characters to a variable.
# ----------------------------------------
quote=$'\042' # " assigned to a variable.
echo "$quote Quoted string $quote and this lies outside the quotes."
echo
# Concatenating ASCII chars in a variable.
triple_underline=$'\137\137\137' # 137 is octal ASCII code for '_'.
echo "$triple_underline UNDERLINE $triple_underline"
echo
ABC=$'\101\102\103\010' # 101, 102, 103 are octal A, B, C.
echo $ABC
echo
escape=$'\033' # 033 is octal for escape.
echo "\"escape\" echoes as $escape"
# no visible output.
echo
exit 0
|
