Sponsored Content
Top Forums Shell Programming and Scripting Shell Scripting Problem - Invalid Back Reference Post 302674349 by johnhisenburg on Thursday 19th of July 2012 12:09:08 PM
Old 07-19-2012
Shell Scripting Problem - Invalid Back Reference

Here is the question...

Create a new script, sub2, taking three parameters...

1.) the string to be replaced
2.) the string with which to replace it
3.) the name of the file in which to make the substitution

...that treats the string to be replaced as plain text instead of as a regular expression.

Hint 1: Try to get the string to be replaced into a shell variable (e.g., $target). Then use a sed command to rewrite any special regular expression characters in that string so that they get treated as text, storing the result in a second shell variable (e.g., $newTarget). Then issue the actual command to perform the substitutions on the file.

Hint 2: For technical reasons, this task is probably easier accomplished in /bin/sh than in /bin/csh. If you insist upon using csh to run your script, you might need to solve this by writing your sed commands into a separate temparary file and using the -f option of sed to run commands from that file.

This is what I've got so far, but for some reason I keep getting the same error message...

Code:
#!/bin/bash
# Script to substitute text

# 0.00 17Jul2012 AI Copy sub1.sh
# 0.01 17Jul2012 AI Convert target to plain text
# 0.02 18Jul2012 AI basename $3

# Usage:
# ./sub2.sh string replace file

echo $1                # Echo options
echo $2
echo $3

plain=`echo "$1" | sed 's/./\\\&/g'`    # Convert target to plain text

basetmp=`basename $3`
tmpfile="/tmp/$basetmp.$$"        # Unique temporary file
sed "s/$plain/$2/g" "$3" > "$tmpfile"    # Edit
mv "$tmpfile" "$3"        # Recover edits


and the error message I get is...

sed: -e expression #1, char 8: Invalid back reference
 

9 More Discussions You Might Find Interesting

1. Shell Programming and Scripting

back reference error

Hi, i am getting this error........ find ./ | sed '/\(*\) \(*\)/\2\1/' Unrecognized command: /\(*\) \(*\)/\2\1/ Any idea??? regards Apoorva Kumar (4 Replies)
Discussion started by: apoorvasharma80
4 Replies

2. Shell Programming and Scripting

Problem with shell script...ORA-00904:invalid identifier

Guys, Please suggest me what's wrong with this script? #!/usr/bin/sh ############################################################################## # Author : Bhagat Singh # # # Date : Nov 13,2006 #... (12 Replies)
Discussion started by: bhagat.singh-j
12 Replies

3. Shell Programming and Scripting

Perl: Getting back reference from s modifier

My input text has the following pattens: func_a(3, 4, 5); I want to replace it with this: func_b(3, 4, 5, 6); I'm trying the following expression, but it does not work: perl -p -e "s/func_a\((.*)?\);/func_b(\1,\n6)/s" <... (8 Replies)
Discussion started by: cooldude
8 Replies

4. Shell Programming and Scripting

Shell Scripting problem

Hi guys, I am a newbie to shell scripting.Please help me to accomplish this task. Its very urgent,I should create a script which will do the following: i) "cd ~joseph/ ; mkdir -p Bing/Bong ;mkdir -p Bing/Bang" and then create 15 ".txt" files with content "Bing Bang Bong" in "Bong"... (1 Reply)
Discussion started by: mahesh_raghu
1 Replies

5. Shell Programming and Scripting

sed error: invalid reference

Hello all, I am using sed to parse a particular part of a string and am having problems. I am getting the following error: sed: -e expression #1, char 28: invalid reference \1 on `s' command's RHS Here is the code I am using: echo "Alarm SET:" echo "" echo "Date: " $DATE echo... (4 Replies)
Discussion started by: dlundwall
4 Replies

6. UNIX for Dummies Questions & Answers

Invalid back reference

The thread can be closed now :D. (3 Replies)
Discussion started by: vaz0r
3 Replies

7. Shell Programming and Scripting

sed back reference error

I am trying to change a single line of a special file whose comment character is ! to show a path to the file in the comment. such as: !!HFSS and mcm path: \Signal_Integrity\Package_SI\Section_Models\C4toTrace\28nm\D6HS\SLC_5-2-5\GZ41_ICZ\NSSS\ to a different path and replace the !!HFSS... (1 Reply)
Discussion started by: mobrien601
1 Replies

8. UNIX for Dummies Questions & Answers

Extract text in sed using back reference

i have a text 20 21 22 23 24 25 26 i want to get 22 using sed back reference. I have used sed 's/{6}\(..\).*/\1/' but, it does not work. I am missing something somewhere. Please help. (5 Replies)
Discussion started by: gotamp
5 Replies

9. Shell Programming and Scripting

sed - use back reference in 2nd command

I have data that looks like this: <Country code="US"><tag>adsf</tag><tag>bdfs</tag></Country><Country code="CA"><tag>asdf</tag><tag>bsdf</tag></Country> I want to grab the country code save it, then drop each new "<..." onto a new line with the country code added to the beginning of each So,... (9 Replies)
Discussion started by: JenniferAmon
9 Replies
GIT-REPLACE(1)							    Git Manual							    GIT-REPLACE(1)

NAME
       git-replace - Create, list, delete refs to replace objects

SYNOPSIS
       git replace [-f] <object> <replacement>
       git replace [-f] --edit <object>
       git replace [-f] --graft <commit> [<parent>...]
       git replace -d <object>...
       git replace [--format=<format>] [-l [<pattern>]]

DESCRIPTION
       Adds a replace reference in refs/replace/ namespace.

       The name of the replace reference is the SHA-1 of the object that is replaced. The content of the replace reference is the SHA-1 of the
       replacement object.

       The replaced object and the replacement object must be of the same type. This restriction can be bypassed using -f.

       Unless -f is given, the replace reference must not yet exist.

       There is no other restriction on the replaced and replacement objects. Merge commits can be replaced by non-merge commits and vice versa.

       Replacement references will be used by default by all Git commands except those doing reachability traversal (prune, pack transfer and
       fsck).

       It is possible to disable use of replacement references for any command using the --no-replace-objects option just after git.

       For example if commit foo has been replaced by commit bar:

	   $ git --no-replace-objects cat-file commit foo

       shows information about commit foo, while:

	   $ git cat-file commit foo

       shows information about commit bar.

       The GIT_NO_REPLACE_OBJECTS environment variable can be set to achieve the same effect as the --no-replace-objects option.

OPTIONS
       -f, --force
	   If an existing replace ref for the same object exists, it will be overwritten (instead of failing).

       -d, --delete
	   Delete existing replace refs for the given objects.

       --edit <object>
	   Edit an object's content interactively. The existing content for <object> is pretty-printed into a temporary file, an editor is
	   launched on the file, and the result is parsed to create a new object of the same type as <object>. A replacement ref is then created
	   to replace <object> with the newly created object. See git-var(1) for details about how the editor will be chosen.

       --raw
	   When editing, provide the raw object contents rather than pretty-printed ones. Currently this only affects trees, which will be shown
	   in their binary form. This is harder to work with, but can help when repairing a tree that is so corrupted it cannot be pretty-printed.
	   Note that you may need to configure your editor to cleanly read and write binary data.

       --graft <commit> [<parent>...]
	   Create a graft commit. A new commit is created with the same content as <commit> except that its parents will be [<parent>...] instead
	   of <commit>'s parents. A replacement ref is then created to replace <commit> with the newly created commit. See
	   contrib/convert-grafts-to-replace-refs.sh for an example script based on this option that can convert grafts to replace refs.

       -l <pattern>, --list <pattern>
	   List replace refs for objects that match the given pattern (or all if no pattern is given). Typing "git replace" without arguments,
	   also lists all replace refs.

       --format=<format>
	   When listing, use the specified <format>, which can be one of short, medium and long. When omitted, the format defaults to short.

FORMATS
       The following format are available:

       o   short: <replaced sha1>

       o   medium: <replaced sha1> -> <replacement sha1>

       o   long: <replaced sha1> (<replaced type>) -> <replacement sha1> (<replacement type>)

CREATING REPLACEMENT OBJECTS
       git-filter-branch(1), git-hash-object(1) and git-rebase(1), among other git commands, can be used to create replacement objects from
       existing objects. The --edit option can also be used with git replace to create a replacement object by editing an existing object.

       If you want to replace many blobs, trees or commits that are part of a string of commits, you may just want to create a replacement string
       of commits and then only replace the commit at the tip of the target string of commits with the commit at the tip of the replacement string
       of commits.

BUGS
       Comparing blobs or trees that have been replaced with those that replace them will not work properly. And using git reset --hard to go back
       to a replaced commit will move the branch to the replacement commit instead of the replaced commit.

       There may be other problems when using git rev-list related to pending objects.

SEE ALSO
       git-hash-object(1) git-filter-branch(1) git-rebase(1) git-tag(1) git-branch(1) git-commit(1) git-var(1) git(1)

GIT
       Part of the git(1) suite

Git 2.17.1							    10/05/2018							    GIT-REPLACE(1)
All times are GMT -4. The time now is 03:23 AM.
Unix & Linux Forums Content Copyright 1993-2022. All Rights Reserved.
Privacy Policy