Replacing single quotes with double quote in a file

sed

I need to replace all single quotes ' contained in /tmp/myfile with " (double quotes)

I'm using this

sed -i 's/'/\"/g' /tmp/myfile

and other combinations but I cannot find a way which works.

Any help please.

Best Answer

To replace single quotes (') it's easiest to put the sed command within double quotes and escape the double quote in the replacement:

$ cat quotes.txt 
I'm Alice
$ sed -e "s/'/\"/g"  quotes.txt 
I"m Alice

Note that the single quote is not special within double quotes, so it must not be escaped.

If, instead one wants to replace backticks (`), as the question originally mentioned, they can be used as-is within single quotes:

$ cat ticks.txt
`this is in backticks`
$ sed -e 's/`/"/g'  ticks.txt
"this is in backticks"

Within double quotes, you'd need to escape the backtick with a backslash, since otherwise it starts an old-form command substitution.

Related Solutions

Text Processing – How to Remove Commas Embedded Within Quotes in a CSV File

If the quotes are balanced, you will want to remove commas between every other quote, this can be expressed in awk like this:

awk -F'"' -v OFS='' '{ for (i=2; i<=NF; i+=2) gsub(",", "", $i) } 1' infile

Output:

123,ABC DEV 23,345,534.202,NAME

Explanation

The -F" makes awk separate the line at the double-quote signs, which means every other field will be the inter-quote text. The for-loop runs gsub, short for globally substitute, on every other field, replacing comma (",") with nothing (""). The 1 at the end invokes the default code-block: { print $0 }.

Double quote value assignments stored in a CSV

Using Sed

sed -e 's/=\([^,]*\)/="\1"/g' file.txt

Using Awk

awk -F, -v OFS=, '{for (f=1;f<=NF;f++) {sub(/=/,"&\"",$f); sub(/$/,"\"",$f)}; print}' file.txt

Or, shorter:

awk -F, -v OFS=, '{for (f=1;f<=NF;f++) {gsub(/=|$/,"&\"",$f)} print}' file.txt

Shorter still:

awk -F, -v OFS=, '{for (f=1;f<=NF;f++) {gsub(/=|$/,"&\"",$f)}} 1' file.txt

Using ex

Ex is designed for file editing, but you can preview changes without actually saving them back to the file like so:

ex -sc '%s/=\([^,]*\)/="\1"/g | %p | q!' file.txt

To actually make the changes and save them to the file, use:

ex -sc '%s/=\([^,]*\)/="\1"/g | x' file.txt

However if you give a pattern which is found nowhere in the file (e.g. there is no = anywhere in the file) then Ex will not exit automatically. Thus for better robustness I usually use printf to pass commands to Ex:

printf '%s\n' '%s/=\([^,]*\)/="\1"/g' %p | ex file.txt

And to save changes:

printf '%s\n' '%s/=\([^,]*\)/="\1"/g' x | ex file.txt