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Annotated edit history of ManipulatingStrings version 7, including all changes. View license author blame.
Rev Author # Line
1 BenStaz 1 !Two Methods For Finding The Length Of a String
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3 *test="This is a string"
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5 Method 1)
6
7 *echo ${#test}
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9 Method 2)
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11 *expr length test
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13 Both will give you the correct length of 16.
3 BenStaz 14
2 BenStaz 15
16 !How can I get a substring of a variable?
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18 Say the variable test contains the string "corndog" but we want just the "dog" part.
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20 echo ${test:4:3} will return just "dog"
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22 The 4 tells us the index of the char that will be the first char in the substring. The 3 tells us how many letters to add starting at the index.
4 BenStaz 23
5 BenStaz 24 !Remove Substrings (uses bash's pattern matching)
4 BenStaz 25
26 Strips *shortest* match of $substring from *front* of $string.
27 *${string#substring}
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29 For example if $string contained "This is a string" and we replaced substring with ''T*'' an echo would result in
30 ''his is a string''
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34 Strips *longest* match of $substring from *front* of $string.
35 *${string##substring}
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37 For example if $string contained "This is a string" and we replaced substring with ''T*'' an echo would result in an empty string. (The longest match was the entire string).
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41 Strips *shortest* match of $substring from *back* of $string.
42 *${string%substring}
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44 For example if $string contained "This is a string" and we replaced substring with ''s*'' an echo would result in
45 ''This is a''
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49 Strips *longest* match of $substring from *back* of $string.
50 *${string%%substring}
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52 For example if $string contained "This is a string" and we replaced substring with ''s*'' an echo would result in
53 ''Thi'' (The longest match)
6 BenStaz 54
55
56 !Concatenate variables.
57
58 *echo ${string1}${string2}
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60 If we did:
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62 *echo $string1string2
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64 then bash would be looking for a variable called ''string1string2'' (which does not exist). This is why the curly brackets are necessary.
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66 Another Example:
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68 *echo ${string1}"Some more Text"
7 BenStaz 69
70 !Brace Expansion
71
72 *echo C{a,u,o}t
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74 Will return ''Cat Cut Cot''
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76 Another example of where this could be useful:
77
78 *mkdir ~~/test/{cat,dog,rabbit}
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80 This will create a ''cat'' , ''dog'' and ''rabbit'' dir in ~~/test/