[Shell programming] File content case substitution

shell programming often encounters strings, file content-case conversions, and choosing the right commands in different scenarios can improve programming efficiency.

Applicable Scenarios

file contents or strings that need to be converted to uppercase and lowercase

string Case Substitution

lowercase Replace Uppercase

Echo " Hello World " TR ' [A-z] ' ' [A-z] ' Echo " Hello World " TR ' [: Lower:] ' ' [: Upper:] '

Uppercase Replace lowercase

Echo " Hello World " TR  ' [A-z] ' ' [A-z] ' Echo " HELLO World " TR  ' [: Upper:] ' ' [: Lower:] '

Uppercase and lowercase swaps

Echo " Hello World " TR ' [A-za-z] ' ' [A-za-z] '

file content case substitution < in situ replacement >

lowercase Replace Uppercase

sed ' s/[a-z]/\u&/g ' filename

Uppercase Replace lowercase

sed ' s/[a-z]/\u&/g ' filename

Replace the first letter of the word with uppercase

sed ' s/\b[a-z]/\u&/g ' filename

file content case substitution < required redirection >

TR 'A- z' 'A- z'< filename1 >filename2 #小写替换成大写TR 'A- z'  'A- z'< filename1 >filename2 #大写替换成小写awk '{print toupper ($)}'filename1 >filename2 #小写替换成大写awk '{print ToLower ($)}'filename1 > Filename2 #大写替换成小写

[Shell programming] File content case substitution