Escaping single quotes with an alias

Question

I am aware that there are many questions asked in the past about escaping single quotes, but none of them addresses this challenge, i.e how to do it with an alias.

I have already successfully defined many aliases to replace sed/awk/grep/perl commands which use regex in the last release of bash (4.4.0(1)).

For instance, the following alias can escape double quotes in any string:

alias esc_double_quotes=$'sed \'s|"|\\\\"|g\''
string="JC's alias to escape \"double quotes\""
echo "$string" | esc_double_quotes
JC's alias to escape \"double quotes\"

However, when it comes to escaping single quotes with an alias, it seems that the mission is impossible.

I have already tried 5 different methods which all fail for different reasons:

# 1) My first technique
alias esc_single_quotes=$'sed \"s|'|\\\\'|g\"'
# 2) My second technique
alias esc_single_quotes="sed 's|'\''|\\\'\''|g'"
# 3) My third technique
alias esc_single_quotes="sed \"s|'|\\\\'|g\""
# 4) Technique inspired from http://stackoverflow.com/questions/1250079/how-to-escape-single-quotes-within-single-quoted-strings?answertab=active#tab-top
alias esc_single_quotes='sed '"'"'s|'|\\\\'|g'"'"
# 5) Technique inspired from http://stackoverflow.com/posts/1315213/revisions
alias esc_single_quotes='sed '\''s|'|\\\\'|g'\'''

Would anyone live up to this impossible challenge & prove me wrong?

The answers to the other question show how to do it and the fact that you're using an alias is irrelevant, the same quoting rules apply (see enzotib's answer which is very similar to Vouze's one here) — don_crissti, Feb 14 '17 at 19:02

score 2 · Accepted Answer · answered Feb 13 '17 at 15:20

2

I can escape everything at once with

printf "%q\n" "$string"

But here is your answer :

alias esc_single_quotes="sed \"s/'/\\\\\\\\'/g\""
echo  "$string" | esc_single_quotes 
JC\'s alias to escape "double quotes"

or :

alias esc_single_quotes='sed "s/'\''/\\\\'\''/g"'
echo  "$string" | esc_single_quotes 
JC\'s alias to escape "double quotes"

answered Feb 13 '17 at 15:20

Vouze

839

Bravo and thanks :-) I won't ask why so many backslashes are needed though. However, the first part of your answer does not answer the question because it escapes also spaces and double quotes. – jean-christophe Manciot Feb 14 '17 at 17:21
You need so many backslashes, because the string will be interpreted twice by the shell and once by sed. So you need 2x2x2=8 backslashes in order to have one at the end. Type "alias" alone to see the first level of interpretation. – Vouze Feb 16 '17 at 09:14

score 1 · Answer 2 · answered Feb 13 '17 at 16:00

1

To help our eyes, let's simplified it:

$ alias esc_single_quotes='sed "s|\x27|\x5c\x5c\x27|g"'

$ echo "this is 'something'"
this is 'something'

$ echo "this is 'something'" |esc_single_quotes
this is \'something\'

answered Feb 13 '17 at 16:00

George Vasiliou

7,913

@jean This solution is nog working? I am just using single quotes and backslash hex numbrs... – George Vasiliou Feb 14 '17 at 17:32

score 0 · Answer 3 · answered Feb 13 '17 at 14:57

0

#!/usr/bin/env bash

function esc_double_quotes() {
    echo $* | sed 's|"|\\\\"|g'
}

answered Feb 13 '17 at 14:57

Stephen Rauch

4,239

@don_crissti, Don't leave me in suspense here, what did I miss? I tried to show the right way to define the alias that he needed. – Stephen Rauch Feb 13 '17 at 15:00
1

@don_crissti, Oh I got that part, but from the help center - Read the question carefully. What, specifically, is the question asking for? Make sure your answer provides that – or a viable alternative. - So I thought it was viable. – Stephen Rauch Feb 13 '17 at 15:08
1

The question talks about how to escape SINLGE quotes, no? – George Vasiliou Feb 13 '17 at 15:48

Escaping single quotes **with** an alias

3 Answers3

Escaping single quotes with an alias