When to use a backslash in a command?
As a consequence, to nest backquoted commands, the backquotes of the inner one have to be escaped using backslashes. Furthermore, backslashes can be used to quote other backslashes and dollar signs (the latter are in fact redundant). If the backquoted command is contained within double quotes, a backslash can also be used to quote a double quote.
Why is there a backslash at the end of the quote?
The\\ escape can cause problems with quoted directory paths that contain a trailing backslash because the closing quote ” at the end of the line will be escaped \\”. To save a directory path with a trailing backslash (\\) requires adding a second backslash to ‘escape the escape’
Are there any commands that use escape characters?
Some commands (e.g. REG and FINDSTR) use the standard escape character of (as used by C, Python, SQL, bash and many other languages.) The escape can cause problems with quoted directory paths that contain a trailing backslash because the closing quote ” at the end of the line will be escaped “.
When to use escaping exclamation marks in Windows?
Escaping Exclamation marks. When the shell is running in EnableDelayedExpansion mode the! character is used to denote a variable and so must be escaped (twice) if you wish to treat it as a regular character: ^^! Escape the Escape character
How to substitute a string for a parameter in Bash?
From the bash documentation: $ {parameter/pattern/string} Pattern substitution. The pattern is expanded to produce a pattern just as in pathname expansion. Parameter is expanded and the longest match of pattern against its value is replaced with string.
How to do double and triple substitution in Bash?
Supposing the value of FOO is a valid variable name (say BAR ), eval \\$$FOO splits the value of BAR into separate words, treats each word as a wildcard pattern, and executes the first word of the result as a command, passing the other words as arguments.
When to use substitution in a shell script?
If parameter is an array variable subscripted with @ or *, the substitution operation is applied to each member of the array in turn, and the expansion is the resultant list. My Shell Scripting books, available in Paperback and eBook formats.