CODEWITHSUNDEEP
bashsed
Jrsys
Jrsys

Reputation: 13

How to escape two slashes coming from string in variable

I'm currently writing a script that will remove directory names from file if not found in system. However, I cannot get my sed command to work.

Current command:

sed -i '/"$row"/d' DirtoDelete.txt

$row expands to //maindir/subdir/testing <--- directory being deleted

but I keep getting the following error:

sed: -e expression #1, char 27: expected newer version of sed

Any ideas what's going on here? Or is there a better way to escape those leading forward slashes?

Upvotes: 1

Views: 623

Answers (3)

hek2mgl
hek2mgl

Reputation: 158240

You can use a different delimiter:

sed -i "\#${row}#d" DirtoDelete.txt

We are using # as the delimiter here because $row does not contain a #. (If you can't ensure that for your input data use something else). Furthermore you need to escape the starting delimiter in this case: \#:

From POSIX sed:

In a context address, the construction "\cBREc", where c is any character other than backslash or newline, shall be identical to "/BRE/". If the character designated by c appears following a backslash, then it shall be considered to be that literal character, which shall not terminate the BRE. For example, in the context address "\xabc\xdefx", the second x stands for itself, so that the BRE is "abcxdef".

Upvotes: 0

slitvinov
slitvinov

Reputation: 5768

You do not have to abuse regular expressions for literate text substitution. awk index function finds substrings. 

$ cat r
d="$1"; shift
awk -v d="$d" '{
    s = $0
    while (i = index(s, d))
        s = substr(s, 1, i - 1) substr(s, i + length(d))
    print s
}' "$@"

Usage:

$ echo '/a/b = /a/b' | sh r 'a/b'
/ = /

Upvotes: 1

glenn jackman
glenn jackman

Reputation: 247210

I know there's a duplicate of this question. Nevertheless:

If you change delimiters, you'll have to escape those in the string, so just bite the bullet and escape the slashes:

$ row=//maindir/subdir/testing
$ echo "${row//\//\\/}"
\/\/maindir\/subdir\/testing
$ echo $'first\nline with '"$row"$'\nlast'
first
line with //maindir/subdir/testing
last
$ echo $'first\nline with '"$row"$'\nlast' | sed "/${row//\//\\/}/d"
first
last

See Shell Parameter Expansion in the bash manual.

Upvotes: 2

Related Questions