Global Search-And-Replace from the Linux command line by OnWorks

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Global Search-And-Replace

vi uses an ex command to perform search-and-replace operations (called “substitution” in vi) over a range of lines or the entire file. To change the word “Line” to “line” for the entire file, we would enter the following command:

:%s/Line/line/g

Let's break this command down into separate items and see what each one does:

Table 12- 5:An example of global search-and-replace syntax

Item Meaning

: The colon character starts an ex command.

% Specifies the range of lines for the operation. % is a shortcut meaning from the first line to the last line. Alternately, the range could have been specified 1,5 (since our file is five lines long), or 1,$ which means “from line 1 to the last line in the file.” If the range of lines is omitted, the operation is only performed on the current line.

Search-And-Replace

s Specifies the operation. In this case, substitution (search-and- replace).

/Line/line/ The search pattern and the replacement text.

g This means “global” in the sense that the search-and-replace is performed on every instance of the search string in the line. If omitted, only the first instance of the search string on each line is replaced.

After executing our search-and-replace command our file looks like this:

The quick brown fox jumped over the lazy dog. It was cool. line 2

line 3

line 4

line 5

The quick brown fox jumped over the lazy dog. It was cool. line 2

line 3

line 4

line 5

We can also specify a substitution command with user confirmation. This is done by adding a “c” to the end of the command. For example:

:%s/line/Line/gc

This command will change our file back to its previous form; however, before each sub- stitution, vi stops and asks us to confirm the substitution with this message:

replace with Line (y/n/a/q/l/^E/^Y)?

Each of the characters within the parentheses is a possible choice as follows:

Table 12-6: Replace Confirmation Keys