In my bash script I have an external (received from user) string, which I should use in sed pattern.
REPLACE="<funny characters here>"
sed "s/KEYWORD/$REPLACE/g"
How can I escape the $REPLACE string so it would be safely accepted by sed as a literal replacement?
NOTE: The KEYWORD is a dumb substring with no matches etc. It is not supplied by user.
Warning: This does not consider newlines. For a more in-depth answer, see this SO-question instead. (Thanks, Ed Morton & Niklas Peter)
Note that escaping everything is a bad idea. Sed needs many characters to be escaped to get their special meaning. For example, if you escape a digit in the replacement string, it will turn in to a backreference.
As Ben Blank said, there are only three characters that need to be escaped in the replacement string (escapes themselves, forward slash for end of statement and & for replace all):
ESCAPED_REPLACE=$(printf '%s\n' "$REPLACE" | sed -e 's/[\/&]/\\&/g')
# Now you can use ESCAPED_REPLACE in the original sed statement
sed "s/KEYWORD/$ESCAPED_REPLACE/g"
If you ever need to escape the KEYWORD string, the following is the one you need:
sed -e 's/[]\/$*.^[]/\\&/g'
And can be used by:
KEYWORD="The Keyword You Need";
ESCAPED_KEYWORD=$(printf '%s\n' "$KEYWORD" | sed -e 's/[]\/$*.^[]/\\&/g');
# Now you can use it inside the original sed statement to replace text
sed "s/$ESCAPED_KEYWORD/$ESCAPED_REPLACE/g"
Remember, if you use a character other than / as delimiter, you need replace the slash in the expressions above wih the character you are using. See PeterJCLaw's comment for explanation.
Edited: Due to some corner cases previously not accounted for, the commands above have changed several times. Check the edit history for details.
The sed command allows you to use other characters instead of / as separator:
sed 's#"http://www\.fubar\.com"#URL_FUBAR#g'
The double quotes are not a problem.
The only three literal characters which are treated specially in the replace clause are / (to close the clause), \ (to escape characters, backreference, &c.), and & (to include the match in the replacement). Therefore, all you need to do is escape those three characters:
sed "s/KEYWORD/$(echo $REPLACE | sed -e 's/\\/\\\\/g; s/\//\\\//g; s/&/\\\&/g')/g"
Example:
$ export REPLACE="'\"|\\/><&!"
$ echo fooKEYWORDbar | sed "s/KEYWORD/$(echo $REPLACE | sed -e 's/\\/\\\\/g; s/\//\\\//g; s/&/\\\&/g')/g"
foo'"|\/><&!bar
Based on Pianosaurus's regular expressions, I made a bash function that escapes both keyword and replacement.
function sedeasy {
sed -i "s/$(echo $1 | sed -e 's/\([[\/.*]\|\]\)/\\&/g')/$(echo $2 | sed -e 's/[\/&]/\\&/g')/g" $3
}
Here's how you use it:
sedeasy "include /etc/nginx/conf.d/*" "include /apps/*/conf/nginx.conf" /etc/nginx/nginx.conf
It's a bit late to respond... but there IS a much simpler way to do this. Just change the delimiter (i.e., the character that separates fields). So, instead of s/foo/bar/ you write s|bar|foo.
And, here's the easy way to do this:
sed 's|/\*!50017 DEFINER=`snafu`#`localhost`\*/||g'
The resulting output is devoid of that nasty DEFINER clause.
It turns out you're asking the wrong question. I also asked the wrong question. The reason it's wrong is the beginning of the first sentence: "In my bash script...".
I had the same question & made the same mistake. If you're using bash, you don't need to use sed to do string replacements (and it's much cleaner to use the replace feature built into bash).
Instead of something like, for example:
function escape-all-funny-characters() { UNKNOWN_CODE_THAT_ANSWERS_THE_QUESTION_YOU_ASKED; }
INPUT='some long string with KEYWORD that need replacing KEYWORD.'
A="$(escape-all-funny-characters 'KEYWORD')"
B="$(escape-all-funny-characters '<funny characters here>')"
OUTPUT="$(sed "s/$A/$B/g" <<<"$INPUT")"
you can use bash features exclusively:
INPUT='some long string with KEYWORD that need replacing KEYWORD.'
A='KEYWORD'
B='<funny characters here>'
OUTPUT="${INPUT//"$A"/"$B"}"
Use awk - it is cleaner:
$ awk -v R='//addr:\\file' '{ sub("THIS", R, $0); print $0 }' <<< "http://file:\_THIS_/path/to/a/file\\is\\\a\\ nightmare"
http://file:\_//addr:\file_/path/to/a/file\\is\\\a\\ nightmare
Here is an example of an AWK I used a while ago. It is an AWK that prints new AWKS. AWK and SED being similar it may be a good template.
ls | awk '{ print "awk " "'"'"'" " {print $1,$2,$3} " "'"'"'" " " $1 ".old_ext > " $1 ".new_ext" }' > for_the_birds
It looks excessive, but somehow that combination of quotes works to keep the ' printed as literals. Then if I remember correctly the vaiables are just surrounded with quotes like this: "$1". Try it, let me know how it works with SED.
These are the escape codes that I've found:
* = \x2a
( = \x28
) = \x29
" = \x22
/ = \x2f
\ = \x5c
' = \x27
? = \x3f
% = \x25
^ = \x5e
sed is typically a mess, especially the difference between gnu-sed and bsd-sed
might just be easier to place some sort of sentinel at the sed side, then a quick pipe over to awk, which is far more flexible in accepting any ERE regex, escaped hex, or escaped octals.
e.g. OFS in awk is the true replacement ::
date | sed -E 's/[0-9]+/\xC1\xC0/g' |
mawk NF=NF FS='\xC1\xC0' OFS='\360\237\244\241'
1 Tue Aug 🤡 🤡:🤡:🤡 EDT 🤡
(tested and confirmed working on both BSD-sed and GNU-sed - the emoji isn't a typo that's what those 4 bytes map to in UTF-8 )
There are dozens of answers out there... If you don't mind using a bash function schema, below is a good answer. The objective below was to allow using sed with practically any parameter as a KEYWORD (F_PS_TARGET) or as a REPLACE (F_PS_REPLACE). We tested it in many scenarios and it seems to be pretty safe. The implementation below supports tabs, line breaks and sigle quotes for both KEYWORD and replace REPLACE.
NOTES: The idea here is to use sed to escape entries for another sed command.
CODE
F_REVERSE_STRING_R=""
f_reverse_string() {
: 'Do a string reverse.
To undo just use a reversed string as STRING_INPUT.
Args:
STRING_INPUT (str): String input.
Returns:
F_REVERSE_STRING_R (str): The modified string.
'
local STRING_INPUT=$1
F_REVERSE_STRING_R=$(echo "x${STRING_INPUT}x" | tac | rev)
F_REVERSE_STRING_R=${F_REVERSE_STRING_R%?}
F_REVERSE_STRING_R=${F_REVERSE_STRING_R#?}
}
# [Ref(s).: https://stackoverflow.com/a/2705678/3223785 ]
F_POWER_SED_ECP_R=""
f_power_sed_ecp() {
: 'Escape strings for the "sed" command.
Escaped characters will be processed as is (e.g. /n, /t ...).
Args:
F_PSE_VAL_TO_ECP (str): Value to be escaped.
F_PSE_ECP_TYPE (int): 0 - For the TARGET value; 1 - For the REPLACE value.
Returns:
F_POWER_SED_ECP_R (str): Escaped value.
'
local F_PSE_VAL_TO_ECP=$1
local F_PSE_ECP_TYPE=$2
# NOTE: Operational characters of "sed" will be escaped, as well as single quotes.
# By Questor
if [ ${F_PSE_ECP_TYPE} -eq 0 ] ; then
# NOTE: For the TARGET value. By Questor
F_POWER_SED_ECP_R=$(echo "x${F_PSE_VAL_TO_ECP}x" | sed 's/[]\/$*.^[]/\\&/g' | sed "s/'/\\\x27/g" | sed ':a;N;$!ba;s/\n/\\n/g')
else
# NOTE: For the REPLACE value. By Questor
F_POWER_SED_ECP_R=$(echo "x${F_PSE_VAL_TO_ECP}x" | sed 's/[\/&]/\\&/g' | sed "s/'/\\\x27/g" | sed ':a;N;$!ba;s/\n/\\n/g')
fi
F_POWER_SED_ECP_R=${F_POWER_SED_ECP_R%?}
F_POWER_SED_ECP_R=${F_POWER_SED_ECP_R#?}
}
# [Ref(s).: https://stackoverflow.com/a/24134488/3223785 ,
# https://stackoverflow.com/a/21740695/3223785 ,
# https://unix.stackexchange.com/a/655558/61742 ,
# https://stackoverflow.com/a/11461628/3223785 ,
# https://stackoverflow.com/a/45151986/3223785 ,
# https://linuxaria.com/pills/tac-and-rev-to-see-files-in-reverse-order ,
# https://unix.stackexchange.com/a/631355/61742 ]
F_POWER_SED_R=""
f_power_sed() {
: 'Facilitate the use of the "sed" command. Replaces in files and strings.
Args:
F_PS_TARGET (str): Value to be replaced by the value of F_PS_REPLACE.
F_PS_REPLACE (str): Value that will replace F_PS_TARGET.
F_PS_FILE (Optional[str]): File in which the replacement will be made.
F_PS_SOURCE (Optional[str]): String to be manipulated in case "F_PS_FILE" was
not informed.
F_PS_NTH_OCCUR (Optional[int]): [1~n] - Replace the nth match; [n~-1] - Replace
the last nth match; 0 - Replace every match; Default 1.
Returns:
F_POWER_SED_R (str): Return the result if "F_PS_FILE" is not informed.
'
local F_PS_TARGET=$1
local F_PS_REPLACE=$2
local F_PS_FILE=$3
local F_PS_SOURCE=$4
local F_PS_NTH_OCCUR=$5
if [ -z "$F_PS_NTH_OCCUR" ] ; then
F_PS_NTH_OCCUR=1
fi
local F_PS_REVERSE_MODE=0
if [ ${F_PS_NTH_OCCUR} -lt -1 ] ; then
F_PS_REVERSE_MODE=1
f_reverse_string "$F_PS_TARGET"
F_PS_TARGET="$F_REVERSE_STRING_R"
f_reverse_string "$F_PS_REPLACE"
F_PS_REPLACE="$F_REVERSE_STRING_R"
f_reverse_string "$F_PS_SOURCE"
F_PS_SOURCE="$F_REVERSE_STRING_R"
F_PS_NTH_OCCUR=$((-F_PS_NTH_OCCUR))
fi
f_power_sed_ecp "$F_PS_TARGET" 0
F_PS_TARGET=$F_POWER_SED_ECP_R
f_power_sed_ecp "$F_PS_REPLACE" 1
F_PS_REPLACE=$F_POWER_SED_ECP_R
local F_PS_SED_RPL=""
if [ ${F_PS_NTH_OCCUR} -eq -1 ] ; then
# NOTE: We kept this option because it performs better when we only need to replace
# the last occurrence. By Questor
# [Ref(s).: https://linuxhint.com/use-sed-replace-last-occurrence/ ,
# https://unix.stackexchange.com/a/713866/61742 ]
F_PS_SED_RPL="'s/\(.*\)$F_PS_TARGET/\1$F_PS_REPLACE/'"
elif [ ${F_PS_NTH_OCCUR} -gt 0 ] ; then
# [Ref(s).: https://unix.stackexchange.com/a/587924/61742 ]
F_PS_SED_RPL="'s/$F_PS_TARGET/$F_PS_REPLACE/$F_PS_NTH_OCCUR'"
elif [ ${F_PS_NTH_OCCUR} -eq 0 ] ; then
F_PS_SED_RPL="'s/$F_PS_TARGET/$F_PS_REPLACE/g'"
fi
# NOTE: As the "sed" commands below always process literal values for the "F_PS_TARGET"
# so we use the "-z" flag in case it has multiple lines. By Quaestor
# [Ref(s).: https://unix.stackexchange.com/a/525524/61742 ]
if [ -z "$F_PS_FILE" ] ; then
F_POWER_SED_R=$(echo "x${F_PS_SOURCE}x" | eval "sed -z $F_PS_SED_RPL")
F_POWER_SED_R=${F_POWER_SED_R%?}
F_POWER_SED_R=${F_POWER_SED_R#?}
if [ ${F_PS_REVERSE_MODE} -eq 1 ] ; then
f_reverse_string "$F_POWER_SED_R"
F_POWER_SED_R="$F_REVERSE_STRING_R"
fi
else
if [ ${F_PS_REVERSE_MODE} -eq 0 ] ; then
eval "sed -i -z $F_PS_SED_RPL \"$F_PS_FILE\""
else
tac "$F_PS_FILE" | rev | eval "sed -z $F_PS_SED_RPL" | tac | rev > "$F_PS_FILE"
fi
fi
}
MODEL
f_power_sed "F_PS_TARGET" "F_PS_REPLACE" "" "F_PS_SOURCE"
echo "$F_POWER_SED_R"
EXAMPLE
f_power_sed "{ gsub(/,[ ]+|$/,\"\0\"); print }' ./ and eliminate" "[ ]+|$/,\"\0\"" "" "Great answer (+1). If you change your awk to awk '{ gsub(/,[ ]+|$/,\"\0\"); print }' ./ and eliminate that concatenation of the final \", \" then you don't have to go through the gymnastics on eliminating the final record. So: readarray -td '' a < <(awk '{ gsub(/,[ ]+/,\"\0\"); print; }' <<<\"$string\") on Bash that supports readarray. Note your method is Bash 4.4+ I think because of the -d in readar"
echo "$F_POWER_SED_R"
IF YOU JUST WANT TO ESCAPE THE PARAMETERS TO THE SED COMMAND
MODEL
# "TARGET" value.
f_power_sed_ecp "F_PSE_VAL_TO_ECP" 0
echo "$F_POWER_SED_ECP_R"
# "REPLACE" value.
f_power_sed_ecp "F_PSE_VAL_TO_ECP" 1
echo "$F_POWER_SED_ECP_R"
IMPORTANT: If the strings for KEYWORD and/or replace REPLACE contain tabs or line breaks you will need to use the "-z" flag in your "sed" command. More details here.
EXAMPLE
f_power_sed_ecp "{ gsub(/,[ ]+|$/,\"\0\"); print }' ./ and eliminate" 0
echo "$F_POWER_SED_ECP_R"
f_power_sed_ecp "[ ]+|$/,\"\0\"" 1
echo "$F_POWER_SED_ECP_R"
NOTE: The f_power_sed_ecp and f_power_sed functions above was made available completely free as part of this project ez_i - Create shell script installers easily!.
Standard recommendation here: use perl :)
echo KEYWORD > /tmp/test
REPLACE="<funny characters here>"
perl -pi.bck -e "s/KEYWORD/${REPLACE}/g" /tmp/test
cat /tmp/test
don't forget all the pleasure that occur with the shell limitation around " and '
so (in ksh)
Var=">New version of \"content' here <"
printf "%s" "${Var}" | sed "s/[&\/\\\\*\\"']/\\&/g' | read -r EscVar
echo "Here is your \"text\" to change" | sed "s/text/${EscVar}/g"
If the case happens to be that you are generating a random password to pass to sed replace pattern, then you choose to be careful about which set of characters in the random string. If you choose a password made by encoding a value as base64, then there is is only character that is both possible in base64 and is also a special character in sed replace pattern. That character is "/", and is easily removed from the password you are generating:
# password 32 characters log, minus any copies of the "/" character.
pass=`openssl rand -base64 32 | sed -e 's/\///g'`;
If you are just looking to replace Variable value in sed command then just remove
Example:
sed -i 's/dev-/dev-$ENV/g' test to sed -i s/dev-/dev-$ENV/g test
I have an improvement over the sedeasy function, which WILL break with special characters like tab.
function sedeasy_improved {
sed -i "s/$(
echo "$1" | sed -e 's/\([[\/.*]\|\]\)/\\&/g'
| sed -e 's:\t:\\t:g'
)/$(
echo "$2" | sed -e 's/[\/&]/\\&/g'
| sed -e 's:\t:\\t:g'
)/g" "$3"
}
So, whats different? $1 and $2 wrapped in quotes to avoid shell expansions and preserve tabs or double spaces.
Additional piping | sed -e 's:\t:\\t:g' (I like : as token) which transforms a tab in \t.
An easier way to do this is simply building the string before hand and using it as a parameter for sed
rpstring="s/KEYWORD/$REPLACE/g"
sed -i $rpstring test.txt
find . | sed -e "s/[^-][^\/]*\// |/g" -e "s/|\([^ ]\)/|-\1/"
Prints out the directory structure of the current directory, which is what I want. Example:
.
|-one
|-two
| |-two_2
| |-two_1
|-test_file
However, when I put it in an alias file (file with all of my aliases), like so:
alias ls_tmp="cd /tmp; find . | sed -e \"s/[^-][^\\/]*\\// |/g\" -e \"s/|\\([^ ]\\)/|-\\1/\""
, which is being loaded with the following sed commands:
// load alias
sprintf(buf, "cat %s|grep \"^alias \"| sed -e \"s/=/ /\" | sed -e \"s/\\\\\\\\//g\"", FILE_NAME);
f = popen(buf, "r");
if (f == NULL) {
fprintf(stderr, "error: failed to init alias commands.\n");
return;
}
, the command actualy executed is actually
cd /tmp; find . | sed -e "s/[^-][^/]*// |/g" -e "s/|([^ ])/|-1/"
Note that all of the backslashes have been stripped, despite the fact that I escaped the backslashes using //.
How do I make this work? I'm confused as to what
sed -e \"s/=/ /\" | sed -e \"s/\\\\\\\\//g
does. Maybe it has to do with the \\\\?
I have a line in a file. like:
1|4|ab|"abnchf "dnvjnkjf" fdvjnfkjnv" 2|12|df|"dskfnkfv "A"
I want to break the into two rows by adding \n at before 4th pipe and after last double quotes.
it should be like:
1|4|ab|"abnchf "dnvjnkjf" fdvjnfkjnv"
2|12|df|"dskfnkfv "A"
i have tried sed command but its not working
sed 's/\(|[^|]*\)(|[^|]*\)(|[^|]*\)|/\1\n|/g'
You may use
sed 's/\([^|]*|\)\{3\}[^|]* /&\n/' file > newfile
See the online demo
Details
\([^|]*|\)\{3\} - three consecutve occurrences of
[^|]* - 0+ chars other than |
| - a pipe symbol
[^|]* - 0+ chars other than |
- a space
The replacement pattern is &\n, the whole match (&) and a newline (\n).
The replacement is only done once per line since I removed the g option.
To avoid overescaping, you may use a POSIX ERE based sed:
sed -E 's/([^|]*\|){3}[^|]* /&\n/' file > newfile
where you do not need to escape capturing parentheses and range/interval quantifier braces (but you have to escape a literal | char).
This might work for you (GNU sed):
sed 's/[^ |]*|/\n&/4' file
Insert a newline before the fourth field delimited by |.
I'm trying to assign elements to an array using ouput from a command. Every example I've found appears to work perfectly whereas my code is only showing 1 element that looks malformed.
Here is the command with output formatted correctly.
[root#probe-eno16777736 nst]# tac "/hns/test_cfg" | sed -n -e "/ip address/,/\!/ p" | grep -B1 "\!" | sed '/!/d' | sed '/\-\-/d'
interface GigabitEthernet0
interface GigabitEthernet0/0/3
interface GigabitEthernet0/0/2.3249
interface GigabitEthernet0/0/2.470
interface GigabitEthernet0/0/2
interface GigabitEthernet0/0/1.3249
interface GigabitEthernet0/0/1.470
interface GigabitEthernet0/0/1
interface GigabitEthernet0/0/0.3419
interface GigabitEthernet0/0/0
interface Loopback32491
interface Loopback3249
interface Loopback470
Here I assign the output to array named "A"
[root#probe-eno16777736 nst]# A=($(tac "/hns/test_cfg" | sed -n -e "/ip address/,/\!/ p" | grep -B1 "\!" | sed '/!/d' | sed '/\-\-/d'))
Here I try to verify each line outputted from command is an element of the array and clearly this is not the case.
[root#probe-eno16777736 nst]# echo ${A[#]}
interface Loopback47091et0/0/0.3419
You should use proper IFS:
IFS=$'\n' declare -a arr=($(tac "/hns/test_cfg" | sed -n -e "/ip address/,/\!/ p" |
grep -B1 "\!" | sed -e '/!/d' -e '/--/d' -e 's/\r//'))
IFS=$'\n' will split the input on newlines while populating array arr.
Print the array:
printf "%s\n" "${arr[#]}"
I'm writing a shell script that splits line of string based on a pattern using sed.
#pattern 'string1','string2','string3'
cat $FILENAME | while read LINE
do
firstPart=$(echo "$LINE" | sed -r "s/'(.*)','(.*)','(.*)'/\1/" )
secondPart=$(echo "$LINE" | sed -r "s/'(.*)','(.*)','(.*)'/\2/" )
thirdPart=$(echo "$LINE" | sed -r "s/'(.*)','(.*)','(.*)'/\3/" )
done
I am able to print them using individual echos, but if I put them in a single echo as show below
#if LINE from FILE is '123','abc','hello'
echo "$firstPart $secondPart"
#this prints " abc" instead of "123 abc"
#try appending a string on echo
echo "$firstPart -"
#this prints " -3" instead of "123 -"
When i tried using sed in a constant string in the code, echo seems fine.
#Correct Echo
SOMESTRING='123','abc','hello'
firstPart=$(echo "$SOMESTRING" | sed -r "s/'(.*)','(.*)','(.*)'/\1/" )
secondPart=$(echo "$SOMESTRING" | sed -r "s/'(.*)','(.*)','(.*)'/\2/" )
thirdPart=$(echo "$SOMESTRING" | sed -r "s/'(.*)','(.*)','(.*)'/\3/" )
echo "$firstPart $secondPart"
#this prints "123 abc"
Is it the correct behavior of sed when input is a LINE from FILE? how can i make it behave as if the LINE is included and declared in the code(like my second example).
It looks to me like you have carriage returns (sometimes written \r) embedded in your strings. So when you do echo "$firstPart -", where firstPart="123\r", it prints two lines:
123
-
...with the second "line" printed on top of (and overwriting) the first. My guess is that you've edited the script with a text editor that uses DOS-style line endings (i.e. each line ends with carriage return followed by linefeed), but the shell expects unix-style line endings (just linefeed) and treats the carriage return as part of the command (e.g. firstPart=$(echo "$SOMESTRING" | sed -r "s/'(.*)','(.*)','(.*)'/\1/" )\r, which will include the \r in firstPart.
If this is the problem, running dos2unix on your script should fix it (and then switch to an editor that doesn't use DOS-style line endings).
When you say SOMESTRING='123','abc','hello' to bash, it strips of the single quotes:
$ echo "$SOMESTRING"
123,abc,hello
If you want to keep them you need to say SOMESTRING="'123','abc','hello'".
This means that your sed patterns are not going work, e.g. firstPart is set to the empty string. If you remove the single quotes from the sed pattern it works.
I would however suggest using IFS to split up simple delimited input:
echo "'123','abc','hello'" | while IFS=, read a b c; do
echo $a
echo $b
echo $c
done
Or briefer:
while IFS=, read a b c; do echo -e "$a\n$b\n$c"; done <<< "'123','abc','hello'"
Output:
'123'
'abc'
'hello'
I am no expert, but I can tell this much that when you are piping the "while" script, the variables used within the while are not available in the main script.
Ex:
If you use the echo statements within the while loop, its shows the parsing by the SED is fine.
You can alternatively use the following syntax to expose these variables in the main script.
while read LINE
do
firstPart=$(echo "$LINE" | sed -r "s/'(.*)','(.*)','(.*)'/\1/" )
secondPart=$(echo "$LINE" | sed -r "s/'(.*)','(.*)','(.*)'/\2/" )
thirdPart=$(echo "$LINE" | sed -r "s/'(.*)','(.*)','(.*)'/\3/" )
done < $FILENAME
SOMESTRING='123','abc','hello'
firstPart=$(echo "$SOMESTRING" | sed "s/\([^,]*\),\([^,]*\),\([^,]*\)/\1/" )
secondPart=$(echo "$SOMESTRING" | sed "s/\([^,]*\),\([^,]*\),\([^,]*\)/\2/" )
thirdPart=$(echo "$SOMESTRING" | sed "s/\([^,]*\),\([^,]*\),\([^,]*\)/\3/" )