Replace First Occurrence Only of Pipe Character in String

Question

I need to remove an extra pipe character at the end of header row of a pipe delimited csv file with sed. The literal string that I am trying to find is COLNAME|

Working on a GCP Windows server. The command I am trying to use:

"C:\Program Files (x86)\GnuWin32\bin\sed.exe" sed '0,/COLNAME"|"/s//COLNAME/' FILENAME

returns the output... sed.exe: -e expression #1, char 3: unterminated `s' command

I'm new to sed and have been playing around with the s command for a while but cannot seem to get the syntax correct.

Any suggestion on how to accomplish this?

Answer 1

If you want to replace COLNAME| with COLNAME"|" in Windows, using the GNU sed, you can use

"C:\Program Files (x86)\GnuWin32\bin\sed.exe" "s/COLNAME|/COLNAME"^""|"^""/g"

Here, COLNAME| matches COLNAME| and COLNAME"^""|"^"" forms the literal COLNAME"|" replacement since COLNAME" ends the quoted string, ^" appends a literal " char to the sed command, "|" appends a | char to the sed command and then ^" appends another literal " to the sed command, and the next " starts the finishing part. The g flag makes it match and replace all occurrences.

If you want to replace COLNAME"|" with COLNAME in Windows, using the GNU sed, you can do that with

"C:\Program Files (x86)\GnuWin32\bin\sed.exe" "s/COLNAME"^""|"^""/COLNAME/g" FILENAME
"C:\Program Files (x86)\GnuWin32\bin\sed.exe" "s/COLNAME\x22|\x22/COLNAME/g" FILENAME
"C:\Program Files (x86)\GnuWin32\bin\sed.exe" "s/COLNAME\d34|\d34/COLNAME/g" FILENAME

Mind that you need to enclose the substitution command with double quotes and to match a double quote, you can't simply use a " or a \", you can match it with an escaped ^", or with \x22, a hex reprentation of the char, or \d34.

Note that in "s/COLNAME"^""|"^""/COLNAME/g", the sed command is built in the following way:

1. "s/COLNAME" sets the beginning
2. ^" appends a literal " char to the sed command
3. "|" - adds | pipe char
4. ^" - adds another "
5. "/COLNAME/g" - finishes off the sed command with the replacement and the global modifier/flag.