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/" )
Related
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 $rpstring test.txt
The below script:
#!/bin/bash
otscurrent="
AAA,33854,4528,38382,12
BBB,83917,12296,96213,13
CCC,20399,5396,25795,21
DDD,27198,4884,32082,15
EEE,2472,981,3453,28
FFF,3207,851,4058,21
GGG,30621,4595,35216,13
HHH,8450,1504,9954,15
III,4963,2157,7120,30
JJJ,51,59,110,54
KKK,87,123,210,59
LLL,573,144,717,20
MMM,617,1841,2458,75
NNN,234,76,310,25
OOO,12433,1908,14341,13
PPP,10627,1428,12055,12
QQQ,510,514,1024,50
RRR,1361,687,2048,34
SSS,1,24,25,96
TTT,0,5,5,100
UUU,294,1606,1900,85
"
IFS="," array1=(${otscurrent})
echo ${array1[4]}
Prints:
$ ./test.sh
12
BBB
I'm trying to get it to just print 12... And I am not even sure how to make it just print row 5 column 4
The variable is an output of a sqlquery that has been parsed with several sed commands to change the formatting to csv.
otscurrent="$(sqlplus64 user/password#dbserverip/db as sysdba #query.sql |
sed '1,11d; /^-/d; s/[[:space:]]\{1,\}/,/g; $d' |
sed '$d'|sed '$d'|sed '$d' | sed '$d' |
sed 's/Used,MB/Used MB/g' |
sed 's/Free,MB/Free MB/g' |
sed 's/Total,MB/Total MB/g' |
sed 's/Pct.,Free/Pct. Free/g' |
sed '1b;/^Name/d' |
sed '/^$/d'
)"
Ultimately I would like to be able to call on a row and column and run statements on the values.
Initially i was piping that into :
awk -F "," 'NR>1{ if($5 < 10) { printf "%-30s%-10s%-10s%-10s%-10s\n", $1,$2,$3,$4,$5"%"; } else { echo "Nothing to do" } }')"
Which works but I couldn't run commands from if else ... or atleaste I didn't know how.
If you have bash 4.0 or newer, an associative array is an appropriate way to store data in this kind of form.
otscurrent=${otscurrent#$'\n'} # strip leading newline present in your sample data
declare -A data=( )
row=0
while IFS=, read -r -a line; do
for idx in "${!line[#]}"; do
data["$row,$idx"]=${line[$idx]}
done
(( row += 1 ))
done <<<"$otscurrent"
This lets you access each individual item:
echo "${data[0,0]}" # first field of first line
echo "${data[9,0]}" # first field of tenth line
echo "${data[9,1]}" # second field of tenth line
"I'm trying to get it to just print 12..."
The issue is that IFS="," splits on commas and there is no comma between 12 and BBB. If you want those to be separate elements, add a newline to IFS. Thus, replace:
IFS="," array1=(${otscurrent})
With:
IFS=$',\n' array1=(${otscurrent})
Output:
$ bash test.sh
12
All you need to print the value of the 4th column on the 5th row is:
$ awk -F, 'NR==5{print $4}' <<< "$otscurrent"
3453
and just remember that in awk row (record) and column (field) numbers start at 1, not 0. Some more examples:
$ awk -F, 'NR==1{print $5}' <<< "$otscurrent"
12
$ awk -F, 'NR==2{print $1}' <<< "$otscurrent"
BBB
$ awk -F, '$5 > 50' <<< "$otscurrent"
JJJ,51,59,110,54
KKK,87,123,210,59
MMM,617,1841,2458,75
SSS,1,24,25,96
TTT,0,5,5,100
UUU,294,1606,1900,85
If you'd like to avoid all of the complexity and simply parse your SQL output to produce what you want without 20 sed commands in between, post a new question showing the raw sqlplus output as the input and what you want finally output and someone will post a brief, clear, simple, efficient awk script to do it all at one time, or maybe 2 commands if you still want an intermediate CSV for some reason.
I am very new to Unix shell script and trying to get some knowledge in shell scripting. Please check my requirement and my approach.
I have a input file having data
ABC = A:3 E:3 PS:6
PQR = B:5 S:5 AS:2 N:2
I am trying to parse the data and get the result as
ABC
A=3
E=3
PS=6
PQR
B=5
S=5
AS=2
N=2
The values can be added horizontally and vertically so I am trying to use an array. I am trying something like this:
myarr=(main.conf | awk -F"=" 'NR!=1 {print $1}'))
echo ${myarr[1]}
# Or loop through every element in the array
for i in "${myarr[#]}"
do
:
echo $i
done
or
awk -F"=" 'NR!=1 {
print $1"\n"
STR=$2
IFS=':' read -r -a array <<< "$STR"
for i in "${!array[#]}"
do
echo "$i=>${array[i]}"
done
}' main.conf
But when I add this code to a .sh file and try to run it, I get syntax errors as
$ awk -F"=" 'NR!=1 {
> print $1"\n"
> STR=$2
> FS= read -r -a array <<< "$STR"
> for i in "${!array[#]}"
> do
> echo "$i=>${array[i]}"
> done
>
> }' main.conf
awk: cmd. line:4: FS= read -r -a array <<< "$STR"
awk: cmd. line:4: ^ syntax error
awk: cmd. line:5: for i in "${!array[#]}"
awk: cmd. line:5: ^ syntax error
awk: cmd. line:8: done
awk: cmd. line:8: ^ syntax error
How can I complete the above expectations?
This is the awk code to do what you want:
$ cat tst.awk
BEGIN { FS="[ =:]+"; OFS="=" }
{
print $1
for (i=2;i<NF;i+=2) {
print $i, $(i+1)
}
print ""
}
and this is the shell script (yes, all a shell script does to manipulate text is call awk):
$ awk -f tst.awk file
ABC
A=3
E=3
PS=6
PQR
B=5
S=5
AS=2
N=2
A UNIX shell is an environment from which to call UNIX tools (find, sort, sed, grep, awk, tr, cut, etc.). It has its own language for manipulating (e.g. creating/destroying) files and processes and sequencing calls to tools but it is NOT intended to be used to manipulate text. The guys who invented shell also invented awk for shell to call to manipulate text.
Read https://unix.stackexchange.com/questions/169716/why-is-using-a-shell-loop-to-process-text-considered-bad-practice and the book Effective Awk Programming, 4th Edition, by Arnold Robbins.
First off, a command that does what you want:
$ sed 's/ = /\n/;y/: /=\n/' main.conf
ABC
A=3
E=3
PS=6
PQR
B=5
S=5
AS=2
N=2
This replaces, on each line, the first (and only) occurrence of = with a newline (the s command), then turns all : into = and all spaces into newlines (the y command). Notice that
this works only because there is a space at the end of the first line (otherwise it would be a bit more involved to get the empty line between the blocks) and
this works only with GNU sed because it substitutes newlines; see this fantastic answer for all the details and how to get it to work with BSD sed.
As for what you tried, there is almost too much wrong with it to try and fix it piece by piece: from the wild mixing of awk and Bash to syntax errors all over the place. I recommend you read good tutorials for both, for example:
The BashGuide
Effective AWK Programming
A Bash solution
Here is a way to solve the same in Bash; I didn't use any arrays.
#!/bin/bash
# Read line by line into the 'line' variable. Setting 'IFS' to the empty string
# preserves leading and trailing whitespace; '-r' prevents interpretation of
# backslash escapes
while IFS= read -r line; do
# Three parameter expansions:
# Replace ' = ' by newline (escape backslash)
line="${line/ = /\\n}"
# Replace ':' by '='
line="${line//:/=}"
# Replace spaces by newlines (escape backslash)
line="${line// /\\n}"
# Print the modified input line; '%b' expands backslash escapes
printf "%b" "$line"
done < "$1"
Output:
$ ./SO.sh main.conf
ABC
A=3
E=3
PS=6
PQR
B=5
S=5
AS=2
N=2
I need to get 1 or more locations from a config file and then check each location for some files. I have an AWK and SED combination which finds the locations and then read the list of files from a text file. I want to check each location for the file and thought to use a bash array to hold the locations.
However for some reason I cannot populate the array from the AWK statement. It appears to me that it loads the complete content into the first element.
If I manually populate the array it works; e.g. replace the line array=$(awk ...
with
array[1]=/docs01/objdata/admin/p1dig
array[2]=/docs02/objdata/admin/p1dig
array[3]=/docs03/objdata/admin/p1dig
array[4]=/docs04/objdata/admin/p1dig
In the code snippet below I have removed the outer (filename) loop and added some debugging context.
#!/bin/bash
declare -a array
OBJECTIVE_CONF=/u01/app/objective/perf/DOS1/config/objConf.xml
FILE=/tmp/DoS1_files.dsv
# IFS=$"/n"
array=$(awk '/<volume>/,/<\/volume>/' $OBJECTIVE_CONF | grep "<path>" | sed "s#<[/]*path>##g" | sed 's/^[ \t]*//' |sed 's/[ \t]*$//' )
element_count=${#array[#]}
echo "element_count is : $element_count "
echo "index is: $index"
echo "${array[$index]}"
echo "filename loop"
index=0
while [ "$index" -lt "$element_count" ]
do
let "index = $index + 1"
echo "index is: $index"
echo "ls ${array[$index]}/filename_from_loop"
done
echo "leaving loop"
The Awk statement gives me the expected result when run from the command line. I AWK for the start and finish XML tags, grep inside that for the PATH and use SED to remove the PATH exm tags and leading and training space.
bash-3.00$ awk '/<volume>/,/<\/volume>/' $OBJECTIVE_CONF | grep "<path>" | sed "s#<[/]*path>##g" | sed 's/^[ \t]*//' |sed 's/[ \t]*$//'
/docs01/objdata/admin/p1dig
/docs02/objdata/admin/p1dig
/docs03/objdata/admin/p1dig
/docs04/objdata/admin/p1dig
$(<command>) substitution does not produce an array. To get an array, use another pair of parentheses:
array=($(<command>))
You can use the readarray statement too :
readarray array < <(command)
the differences than just assign, like array=($(<command>)), is that you have more control on the final array, (man)
the < <(command) is for function/command expansion without a child process.
I need to assign the results from a grep to an array... for example
grep -n "search term" file.txt | sed 's/:.*//'
This resulted in a bunch of lines with line numbers in which the search term was found.
1
3
12
19
What's the easiest way to assign them to a bash array? If I simply assign them to a variable they become a space-separated string.
To assign the output of a command to an array, you need to use a command substitution inside of an array assignment. For a general command command this looks like:
arr=( $(command) )
In the example of the OP, this would read:
arr=($(grep -n "search term" file.txt | sed 's/:.*//'))
The inner $() runs the command while the outer () causes the output to be an array. The problem with this is that it will not work when the output of the command contains spaces. To handle this, you can set IFS to \n.
IFS=$'\n' arr=($(grep -n "search term" file.txt | sed 's/:.*//'))
You can also cut out the need for sed by performing an expansion on each element of the array:
arr=($(grep -n "search term" file.txt))
arr=("${arr[#]%%:*}")
Space-separated strings are easily traversable in bash.
# save the ouput
output=$(grep -n "search term" file.txt | sed 's/:.*//')
# iterating by for.
for x in $output; do echo $x; done;
# awk
echo $output | awk '{for(i=1;i<=NF;i++) print $i;}'
# convert to an array
ar=($output)
echo ${ar[3]} # echos 4th element
if you are thinking space in file name use find . -printf "\"%p\"\n"
#Charles Duffy linked the Bash anti-pattern docs in a comment, and those give the most correct answer:
readarray -t arr < <(grep -n "search term" file.txt | sed 's/:.*//')
His comment:
Note that array=( $(command) ) is considered an antipattern, and is the topic of BashPitfalls #50. – Charles Duffy Nov 16, 2020 at 14:07