How can I print the first matched line using sed or grep? - bash

I have a config file where each line is in a format say UniqueOption = SomeValue:
$ cat somefile
option1sub1 = yes
option1sub2 = 1234
...
option1subn = xxxx
option2 = 2345
option3 = no
...
I want to deal with each value of "option1" in a loop. but, sed or grep give me all of option1 in one time.
How could I achieve that using sed or grep, getting a single option1 line at a time?


pipe the output of grep to a while loop:
grep 'option1' somefile | while read line
do
echo "single option is in var $line"
done


Solution 1st: Following awk may help you on same to get the value of option1 string's last value.
awk -F" = " '/^option1/{print $NF}' Input_file
Solution 2nd: Above will print all values of string option1 in case you need only very first value of string option1 then use following.
awk -F" = " '/^option1/{print $NF;exit}' Input_file


The following will parse out all sub-options for option1 in the file file.conf and save them in a bash array. The options are then easily accessed from that array.
#!/bin/bash
while IFS= read -r data; do
opt1+=( "$data" )
done < <( awk -F ' *= *' '$1 ~ /^option1/ { print $2 }' file.conf )
printf 'Option 1, sub-option 1 is "%s"\n' "${opt1[0]}"
Output:
Option 1, sub-option 1 is "yes"
The awk script will return everything after the = (and any spaces), which allows you to store data that contains multiple words. Only the lines starting with option1 in the configuration file are processed.
This would be adapted to parse the whole configuration file into a single structure, possibly using an associative array in a sufficiently recent version of bash.


Already we can see few awesome answers but as you asked something with grep, you can use one of the following if you want.
For all values
grep option1 m | cut -d "=" -f2 | awk '{$1=$1};1'
For first value
grep option1 m | cut -d "=" -f2 | awk '{$1=$1};1' | head -1
Here: cut is used to cut the second option uisng dilimiter =; awk is used to trim the spaces in output and head is used to print first occurrence


With sed
sed '/^option1.* = /!d;s///' somefile
With gnu grep 2.20 (support of pcre)
grep -oP '^option1.* = \K.*' somefile
If you want to get only the first match
sed '/^option1.* = /!d;s///;q' somefile
grep -m1 -oP '^option1.* = \K.*' somefile

Related

xargs and cut: getting `cut` fields of a csv to bash variable

I am using xargs in conjuction with cut but I am unsure how to get the output of cut to a variable which I can pipe to use for further processing.
So, I have a text file like so:
test.txt:
/some/path/to/dir,filename.jpg
/some/path/to/dir2,filename2.jpg
...
I do this:
cat test.txt | xargs -L1 | cut -d, -f 1,2
/some/path/to/dir,filename.jpg
but what Id like to do is:
cat test.txt | xargs -L1 | cut -d, -f 1,2 | echo $1 $2
where $1 and $2 are /some/path/to/dir and filename.jpg
I am stumped that I cannot seem to able to achieve this..

You may want to say something like:
#!/bin/bash
while IFS=, read -r f1 f2; do
echo ./mypgm -i "$f1" -o "$f2"
done < test.txt
IFS=, read -r f1 f2 reads a line from test.txt one by one,
splits the line on a comma, then assigns the variables f1 and f2
to the fields.
The line echo .. is for the demonstration purpose. Replace the
line with your desired command using $f1 and $f2.

Try this:
cat test.txt | awk -F, '{print $1, $2}'
From man xargs:
xargs [-L number] [utility [argument ...]]
-L number
Call utility for every number non-empty lines read.
From man awk:
Awk scans each input file for lines that match any of a set of patterns specified literally in prog or in one or more files specified as -f progfile.
So you don't have to use xargs -L1 as you don't pass the utility to call.
Also from man awk:
The -F fs option defines the input field separator to be the regular expression fs.
So awk -F, can replace the cut -d, part.
The fields are denoted $1, $2, ..., while $0 refers to the entire line.
So $1 is for the first column, $2 is for the second one.
An action is a sequence of statements. A statement can be one of the following:
print [ expression-list ] [ > expression ]
An empty expression-list stands for $0.
The print statement prints its argument on the standard output (or on a file if > file or >> file is present or on a pipe if | cmd is present), separated by the current output field separator, and terminated by the output record separator.
Put all these together, cat test.txt | awk -F, '{print $1, $2}' would achieve that you want.

Print line based on 2nd field value, without using a loop

I try to retrieve a line from a file without using a loop.
myFile.txt
val1;a;b;c
val2;b;d;e
val3;c;r;f
I would like to get the line where the second column is b.
If I do grep "b" myFile.txt then both first and second line will be outputed.
If I do cat myFile.txt | cut -d ';' -f2 | grep "b" then the output will just be b whereas I'd like to get the full line val2;b;d;e.
Is there a way of reaching the desired results without using a loop as below ? My file being huge it wouldn't be nice looping through it again and again.
while read line; do
if [ `echo $line | cut -d ';' -f2` = "b" ]; then
echo $line
fi
done < myFile.txt

Given your input file, The below one-liner should work:
awk -F";" '$2 == "b" {print}' myFile.txt
Explanation:
awk -F";" ##Field Separator as ";"
'$2 == "b" ##Searches for "b" in the second column($2)
{print}' ##prints the searched line

Using:
grep:
grep '^[^;]*;b;' myFile.txt
sed:
sed '/^[^;]*;b;/!d' myFile.txt
Output is the same for both:
val2;b;d;e

parse output in bash

My file looks like
//
[297]((((21:0.125204,20:0.125204):0.00994299,(28:0.0790047,(7:0.0146105,5:0.0146105):0.0643943):0.0561423):0.0578754,(((23:0.0386924,((((26:0.0160606,22:0.0160606):0.00378,(19:0.0160596,16:0.0160596):0.00378096):0.00242531,12:0.0222659):0.0146336,((29:0.0160393,(17:0.00712055,14:0.00712055):0.00891871):0.0195068,11:0.0355461):0.00135346):0.00179282):0.0468499,4:0.0855423):0.0451632,((25:0.059669,(30:0.0155625,13:0.0155625):0.0441064):0.0223692,(3:0.0288957,1:0.0288957):0.0531425):0.0486673):0.062317):0.60861,((((((62:0.00660739,58:0.00660739):0.011345,(70:0.00496959,54:0.00496959):0.0129828):0.0065665,((68:0.00291155,53:0.00291155):0.0178013,(66:0.0163583,((65:0.0045002,(69:0.00305355,59:0.00305355):0.00144664):0.000757378,(61:0.00311373,52:0.00311373):0.00214385):0.0111007):0.00435459):0.003806):0.123648,(76:0.0395418,(40:0.00641035,34:0.00641035):0.0331314):0.108625):0.0327298,((((46:0.00103749,42:0.00103749):0.0373456,(48:0.0259862,41:0.0259862):0.0123969):0.00173179,(47:0.0275497,39:0.0275497):0.0125652):0.106275,((((44:0.00708562,36:0.00708562):0.0773928,(37:0.025,27:0.025):0.0594785):0.00501024,18:0.0894887):0.0248315,(15:0.0649576,6:0.0649576):0.0493626):0.0320701):0.0345064):0.0680223,((((80:0.0173948,73:0.0173948):0.0162433,(67:0.0129751,((63:0.00435012,57:0.00435012):0.00727273,(60:0.00848091,(64:0.00386096,((56:0.00203231,55:0.00203231):0.00103,51:0.0030623):0.000798654):0.00461996):0.00314194):0.00135223):0.0206631):0.0296773,(33:0.0415374,((75:0.0372575,(45:0.0371022,38:0.0371022):0.000155282):0.0029007,((43:0.0101608,32:0.0101608):0.0242563,31:0.0344171):0.00574108):0.00137926):0.021778):0.147776,((((74:0.0336172,((79:0.0258073,(77:0.0203659,(78:0.00390563,72:0.00390563):0.0164602):0.00544144):0.00767555,49:0.0334829):0.000134364):0.0132633,(35:0.0137148,24:0.0137148):0.0331656):0.0721567,(10:0.0147938,8:0.0147938):0.104243):0.0343567,((71:0.0427659,50:0.0427659):0.0221428,(9:0.0467372,2:0.0467372):0.0181715):0.0884852):0.0576977):0.0378275):0.552713);
[2271]((((21:0.125204,20:0.125204):0.00994299,(28:0.0790047,(7:0.0146105,5:0.0146105):0.0643943):0.0561423):0.0578754,(((23:0.0386924,((((26:0.0160606,22:0.0160606):0.00378,(19:0.0160596,16:0.0160596):0.00378096):0.00242531,12:0.0222659):0.0146336,((29:0.0160393,(17:0.00712055,14:0.00712055):0.00891871):0.0195068,11:0.0355461):0.00135346):0.00179282):0.0468499,4:0.0855423):0.0451632,((25:0.059669,(30:0.0155625,13:0.0155625):0.0441064):0.0223692,(3:0.0288957,1:0.0288957):0.0531425):0.0486673):0.062317):0.60861,((((47:0.0363305,(((62:0.00660739,58:0.00660739):0.011345,(70:0.00496959,54:0.00496959):0.0129828):0.0065665,((68:0.00291155,53:0.00291155):0.0178013,(66:0.0163583,((65:0.0045002,(69:0.00305355,59:0.00305355):0.00144664):0.000757378,(61:0.00311373,52:0.00311373):0.00214385):0.0111007):0.00435459):0.003806):0.0118116):0.111837,(76:0.0395418,(40:0.00641035,34:0.00641035):0.0331314):0.108625):0.0327298,((((46:0.00103749,42:0.00103749):0.0373456,(48:0.0259862,41:0.0259862):0.0123969):0.00173179,39:0.0401149):0.106275,((((44:0.00708562,36:0.00708562):0.0773928,(37:0.025,27:0.025):0.0594785):0.00501024,18:0.0894887):0.0248315,(15:0.0649576,6:0.0649576):0.0493626):0.0320701):0.0345064):0.0680223,((((80:0.0173948,73:0.0173948):0.0162433,(67:0.0129751,((63:0.00435012,57:0.00435012):0.00727273,(60:0.00848091,(64:0.00386096,((56:0.00203231,55:0.00203231):0.00103,51:0.0030623):0.000798654):0.00461996):0.00314194):0.00135223):0.0206631):0.0296773,(33:0.0415374,((75:0.0372575,(45:0.0371022,38:0.0371022):0.000155282):0.0029007,((43:0.0101608,32:0.0101608):0.0242563,31:0.0344171):0.00574108):0.00137926):0.021778):0.147776,((((74:0.0336172,((79:0.0258073,(77:0.0203659,(78:0.00390563,72:0.00390563):0.0164602):0.00544144):0.00767555,49:0.0334829):0.000134364):0.0132633,(35:0.0137148,24:0.0137148):0.0331656):0.0721567,(10:0.0147938,8:0.0147938):0.104243):0.0343567,((71:0.0427659,50:0.0427659):0.0221428,(9:0.0467372,2:0.0467372):0.0181715):0.0884852):0.0576977):0.0378275):0.552713);
[687]((((21:0.125204,20:0.125204):0.00994299,(28:0.0790047,(7:0.0146105,5:0.0146105):0.0643943):0.0561423):0.0578754,((4:0.128716,(23:0.0386924,((((26:0.0160606,22:0.0160606):0.00378,(19:0.0160596,16:0.0160596):0.00378096):0.00242531,12:0.0222659):0.0146336,((29:0.0160393,(17:0.00712055,14:0.00712055):0.00891871):0.0195068,11:0.0355461):0.00135346):0.00179282):0.0900232):0.0019898,((25:0.059669,(30:0.0155625,13:0.0155625):0.0441064):0.0223692,(3:0.0288957,1:0.0288957):0.0531425):0.0486673):0.062317):0.60861,((((47:0.0363305,(((62:0.00660739,58:0.00660739):0.011345,(70:0.00496959,54:0.00496959):0.0129828):0.0065665,((68:0.00291155,53:0.00291155):0.0178013,(66:0.0163583,((65:0.0045002,(69:0.00305355,59:0.00305355):0.00144664):0.000757378,(61:0.00311373,52:0.00311373):0.00214385):0.0111007):0.00435459):0.003806):0.0118116):0.111837,(76:0.0395418,(40:0.00641035,34:0.00641035):0.0331314):0.108625):0.0327298,((((46:0.00103749,42:0.00103749):0.0373456,(48:0.0259862,41:0.0259862):0.0123969):0.00173179,39:0.0401149):0.106275,((((44:0.00708562,36:0.00708562):0.0773928,(37:0.025,27:0.025):0.0594785):0.00501024,18:0.0894887):0.0248315,(15:0.0649576,6:0.0649576):0.0493626):0.0320701):0.0345064):0.0680223,((((80:0.0173948,73:0.0173948):0.0162433,(67:0.0129751,((63:0.00435012,57:0.00435012):0.00727273,(60:0.00848091,(64:0.00386096,((56:0.00203231,55:0.00203231):0.00103,51:0.0030623):0.000798654):0.00461996):0.00314194):0.00135223):0.0206631):0.0296773,(33:0.0415374,((75:0.0372575,(45:0.0371022,38:0.0371022):0.000155282):0.0029007,((43:0.0101608,32:0.0101608):0.0242563,31:0.0344171):0.00574108):0.00137926):0.021778):0.147776,((((74:0.0336172,((79:0.0258073,(77:0.0203659,(78:0.00390563,72:0.00390563):0.0164602):0.00544144):0.00767555,49:0.0334829):0.000134364):0.0132633,(35:0.0137148,24:0.0137148):0.0331656):0.0721567,(10:0.0147938,8:0.0147938):0.104243):0.0343567,((71:0.0427659,50:0.0427659):0.0221428,(9:0.0467372,2:0.0467372):0.0181715):0.0884852):0.0576977):0.0378275):0.552713);
[186]((((21:0.125204,20:0.125204):0.00994299,(28:0.0790047,(7:0.0146105,5:0.0146105):0.0643943):0.0561423):0.0578754,((4:0.128716,(23:0.0386924,((((26:0.0160606,22:0.0160606):0.00378,(19:0.0160596,16:0.0160596):0.00378096):0.00242531,12:0.0222659):0.0146336,((29:0.0160393,(17:0.00712055,14:0.00712055):0.00891871):0.0195068,11:0.0355461):0.00135346):0.00179282):0.0900232):0.0019898,((25:0.059669,(30:0.0155625,13:0.0155625):0.0441064):0.0223692,(3:0.0288957,1:0.0288957):0.0531425):0.0486673):0.062317):0.60861,((((47:0.0363305,(((62:0.00660739,58:0.00660739):0.011345,(70:0.00496959,54:0.00496959):0.0129828):0.0065665,((68:0.00291155,53:0.00291155):0.0178013,(66:0.0163583,((65:0.0045002,(69:0.00305355,59:0.00305355):0.00144664):0.000757378,(61:0.00311373,52:0.00311373):0.00214385):0.0111007):0.00435459):0.003806):0.0118116):0.111837,(76:0.0395418,(40:0.00641035,34:0.00641035):0.0331314):0.108625):0.0327298,((((44:0.00708562,36:0.00708562):0.0773928,(37:0.025,27:0.025):0.0594785):0.00501024,18:0.0894887):0.0248315,(15:0.0649576,6:0.0649576):0.0493626):0.0665766):0.0680223,((((80:0.0173948,73:0.0173948):0.0162433,(67:0.0129751,((63:0.00435012,57:0.00435012):0.00727273,(60:0.00848091,(64:0.00386096,((56:0.00203231,55:0.00203231):0.00103,51:0.0030623):0.000798654):0.00461996):0.00314194):0.00135223):0.0206631):0.0296773,(33:0.0415374,((75:0.0372575,(45:0.0371022,38:0.0371022):0.000155282):0.0029007,((43:0.0101608,32:0.0101608):0.0242563,31:0.0344171):0.00574108):0.00137926):0.021778):0.147776,((((74:0.0336172,((79:0.0258073,(77:0.0203659,(78:0.00390563,72:0.00390563):0.0164602):0.00544144):0.00767555,49:0.0334829):0.000134364):0.0132633,(35:0.0137148,24:0.0137148):0.0331656):0.0721567,(10:0.0147938,8:0.0147938):0.104243):0.0343567,((((46:0.00103749,42:0.00103749):0.0373456,(48:0.0259862,41:0.0259862):0.0123969):0.00173179,39:0.0401149):0.0339623,((71:0.0427659,50:0.0427659):0.0221428,(9:0.0467372,2:0.0467372):0.0181715):0.00916857):0.0793167):0.0576977):0.0378275):0.552713);
So after the first line every line starts with a number in brackets. I would need to grep the number in brackets and output it into a new file (without [) ..how would that be done>

grep -Po '(?<=\[)\d+(?=\])' file > new_file
-P for Perl regexs so it is possible to use:
\d for a digit
positive lookbehind and positive lookahead ((?<=\[) and (?=\]))
-o for only matching

Another possibility if your grep doesn't support the -P option but awk is available could be this:
awk -F '[][]' '{ if ($2 != "") print $2 }' file > new_file
-F tells awk to accept both ] and [ as a field delimiter, $2 then contains the number you want and is printed.

In three steps using simple commands:
grep -v "//" inputfile | cut -d"[" -f2 | cut -d"]" -f1
In sed can you remove everything outside the []:
grep -v "//" inputfile | sed 's/.*\[\(.*\)].*/\1/'

Awk: Drop last record separator in one-liner

I have a simple command (part of a bash script) that I'm piping through awk but can't seem to suppress the final record separator without then piping to sed. (Yes, I have many choices and mine is sed.) Is there a simpler way without needing the last pipe?
dolls = $(egrep -o 'alpha|echo|november|sierra|victor|whiskey' /etc/passwd \
| uniq | awk '{IRS="\n"; ORS=","; print}'| sed s/,$//);
Without the sed, this produces output like echo,sierra,victor, and I'm just trying to drop the last comma.

You don't need awk, try:
egrep -o ....uniq|paste -d, -s
Here is another example:
kent$ echo "a
b
c"|paste -d, -s
a,b,c
Also I think your chained command could be simplified. awk could do all things in an one-liner.

Instead of egrep, uniq, awk, sed etc, all this can be done in one single awk command:
awk -F":" '!($1 in a){l=l $1 ","; a[$1]} END{sub(/,$/, "", l); print l}' /etc/password

Here is a small and quite straightforward one-liner in awk that suppresses the final record separator:
echo -e "alpha\necho\nnovember" | awk 'y {print s} {s=$0;y=1} END {ORS=""; print s}' ORS=","
Gives:
alpha,echo,november
So, your example becomes:
dolls = $(egrep -o 'alpha|echo|november|sierra|victor|whiskey' /etc/passwd | uniq | awk 'y {print s} {s=$0;y=1} END {ORS=""; print s}' ORS=",");
The benefit of using awk over paste or tr is that this also works with a multi-character ORS.

Since you tagged it bash here is one way of doing it:
#!/bin/bash
# Read the /etc/passwd file in to an array called names
while IFS=':' read -r name _; do
names+=("$name");
done < /etc/passwd
# Assign the content of the array to a variable
dolls=$( IFS=, ; echo "${names[*]}")
# Display the value of the variable
echo "$dolls"

echo "a
b
c" |
mawk 'NF-= _==$NF' FS='\n' OFS=, RS=
a,b,c

Extracting minimum and maximum from line number grep

Currently, I have a command in a bash script that greps for a given string in a text file and prints the line numbers only using sed ...
grep -n "<string>" file.txt | sed -n 's/^\([0-9]*\).*/\1/p'
The grep could find multiple matches, and thus, print multiple line numbers. From this command's output, I would like to extract the minimum and maximum values, and assign those to respective bash variables. How could I best modify my existing command or add new commands to accomplish this? If using awk or sed will be necessary, I have a preference of using sed. Thanks!

You can get the minimum and maximum with this:
grep -n "<string>" input | sed -n -e 's/^\([0-9]*\).*/\1/' -e '1p;$p'
You can also read them into an array:
F=($(grep -n "<string>" input | sed -n -e 's/^\([0-9]*\).*/\1/' -e '1p;$p'))
echo ${F[0]} # min
echo ${F[1]} # max

grep -n "<string>" file.txt | sed -n -e '1s/^\([0-9]*\).*/\1/p' -e '$s/^\([0-9]*\).*/\1/p'

grep .... |awk -F: '!f{print $1;f=1} END{print $1}'

Here's how I'd do it, since grep -n 'pattern' file prints output in the format line number:line contents ...
minval=$(grep -n '<string>' input | cut -d':' -f1 | sort -n | head -1)
maxval=$(grep -n '<string>' input | cut -d':' -f1 | sort -n | tail -1)
the cut -d':' -f1 command splits the grep output around the colon and pulls out only the first field (the line numbers), sort -n sorts the numeric line numbers in ascending order (which they would already be in, but it's good practice to ensure it), then head -1 and tail -1 remove the first, and last value in the sorted list respectively, i.e. the minimum and maximum values and assign them to variables $minval and $maxval respectively.
Hope this helps!
Edit: Turns out you can't do it the way I had it originally, since echoing out a list of newline-separated values apparently concatenates them into one line.

It can be done with one process. Like this:
awk '/expression/{if(!n)print NR;n=NR} END {print n}' file.txt
Then You can assign to an array (as perreal suggested). Or You can modify this script and assign to varables using eval
eval $(awk '/expression/{if(!n)print "A="NR;n=NR} END {print "B="n}' file.txt)
echo $A
echo $B
Output (file.txt contains three lines of expression)
1
3

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