I'm trying to set the value of a variable to one line of a file, over and over.
for i in {1..5}
do
THIS = "grep -m $i'[a-z]' newdict2" | tail -1
echo $THIS
done
What's the trick to this black magic?
It's actually easier to run it with sed than tail and grep's -m option:
for i in {1..5}
do
THIS=$(grep -e '[a-z]' newdict2 | sed -ne "${i}p")
echo "$THIS"
done
If you start from 1 to x, other ways to solve it is through line reading in a loop:
while IFS= read -r THIS; do
echo "$THIS"
done < <(grep -e '[a-z]' newdict2)
And through awk:
while IFS= read -r THIS; do
echo "$THIS"
done < (awk '/[a-z]/ && ++i <= 5' newdict2)
Another awk version with different initial value:
while IFS= read -r THIS; do
echo "$THIS"
done < (awk 'BEGIN { i = 2 } /[a-z]/ && i++ <= 5' newdict2)
It's better to find the occurrences once, and loop over them.
grep -m "$i" '[a-z]' newdict |
nl |
while read i THIS; do
echo "$THIS"
done
If you don't need $i for anything inside the loop, remove nl and just read THIS.
Note also the use of double quotes around variable interpolations.
Related
I'm still new to the shell and need some help.
I have a file stapel_old.
Also I have in the same directory files like english_old_sync, math_old_sync and vocabulary_old_sync.
The content of stapel_old is:
english
math
vocabulary
The content of e.g. english is:
basic_grammar.md
spelling.md
orthography.md
I want to manipulate all files which are given in stapel_old like in this example:
take the first line of stapel_old 'english', (after that math, and so on)
convert in this case english to english_old_sync, (or after that what is given in second line, e.g. math to math_old_sync)
search in english_old_sync line by line for the pattern '.md'
And append to each line after .md :::#a1
The result should be e.g. of english_old_sync:
basic_grammar.md:::#a1
spelling.md:::#a1
orthography.md:::#a1
of math_old_sync:
geometry.md:::#a1
fractions.md:::#a1
and so on. stapel_old should stay unchanged.
How can I realize that?
I tried with sed -n, while loop (while read -r line), and I'm feeling it's somehow the right way - but I still get errors and not the expected result after 4 hours inspecting and reading.
Thank you!
EDIT
Here is the working code (The files are stored in folder 'olddata'):
clear
echo -e "$(tput setaf 1)$(tput setab 7)Learning directories:$(tput sgr 0)\n"
# put here directories which should not become flashcards, command: | grep -v 'name_of_directory_which_not_to_learn1' | grep -v 'directory2'
ls ../ | grep -v 00_gliederungsverweise | grep -v 0_weiter | grep -v bibliothek | grep -v notizen | grep -v Obsidian | grep -v z_nicht_uni | tee olddata/stapel_old
# count folders
echo -ne "\nHow much different folders: " && wc -l olddata/stapel_old | cut -d' ' -f1 | tee -a olddata/stapel_old
echo -e "Are this learning directories correct? [j ODER y]--> yes; [Other]-->no\n"
read lernvz_korrekt
if [ "$lernvz_korrekt" = j ] || [ "$lernvz_korrekt" = y ];
then
read -n 1 -s -r -p "Learning directories correct. Press any key to continue..."
else
read -n 1 -s -r -p "Learning directories not correct, please change in line 4. Press any key to continue..."
exit
fi
echo -e "\n_____________________________\n$(tput setaf 6)$(tput setab 5)Found cards:$(tput sgr 0)$(tput setaf 6)\n"
#GET && WRITE FOLDER NAMES into olddata/stapel_old
anzahl_zeilen=$(cat olddata/stapel_old |& tail -1)
#GET NAMES of .md files of every stapel and write All to 'stapelname'_old_sync
i=0
name="var_$i"
for (( num=1; num <= $anzahl_zeilen; num++ ))
do
i="$((i + 1))"
name="var_$i"
name=$(cat olddata/stapel_old | sed -n "$num"p)
find ../$name/ -name '*.md' | grep -v trash | grep -v Obsidian | rev | cut -d'/' -f1 | rev | tee olddata/$name"_old_sync"
done
(tput sgr 0)
I tried to add:
input="olddata/stapel_old"
while IFS= read -r line
do
sed -n "$line"p olddata/stapel_old
done < "$input"
The code to change only the english_old_sync is:
lines=$(wc -l olddata/english_old_sync | cut -d' ' -f1)
for ((num=1; num <= $lines; num++))
do
content=$(sed -n "$num"p olddata/english_old_sync)
sed -i "s/"$content"/""$content":::#a1/g"" olddata/english_old_sync
done
So now, this need to be a inner for-loop, of a outer for-loop which holds the variable for english, right?
stapel_old should stay unchanged.
You could try a while + read loop and embed sed inside the loop.
#!/usr/bin/env bash
while IFS= read -r files; do
echo cp -v "$files" "${files}_old_sync" &&
echo sed '/^.*\.md$/s/$/:::#a1/' "${files}_old_sync"
done < olddata/staple_old
convert in this case english to english_old_sync, (or after that what is given in second line, e.g. math to math_old_sync)
cp copies the file with a new name, if the goal is renaming the original file name from the content of the file staple_old then change cp to mv
The -n and -i flag from sed was ommited , include it, if needed.
The script also assumes that there are no empty/blank lines in the content of staple_old file. If in case there are/is add an addition test after the line where the do is.
[[ -n $files ]] || continue
It also assumes that the content of staple_old are existing files. Just in case add an additional test.
[[ -e $files ]] || { printf >&2 '%s no such file or directory.\n' "$files"; continue; }
Or an if statement.
if [[ ! -e $files ]]; then
printf >&2 '%s no such file or directory\n' "$files"
continue
fi
See also help test
See also help continue
Combining them all together should be something like:
#!/usr/bin/env bash
while IFS= read -r files; do
[[ -n $files ]] || continue
[[ -e $files ]] || {
printf >&2 '%s no such file or directory.\n' "$files"
continue
}
echo cp -v "$files" "${files}_old_sync" &&
echo sed '/^.*\.md$/s/$/:::#a1/' "${files}_old_sync"
done < olddata/staple_old
Remove the echo's If you're satisfied with the output so the script could copy/rename and edit the files.
i want to turn a string like
AaAa
into
a string like this
%<41>%<61>%<41>%<61>
Simple enough with the programming languages i am familar with, but with bash i can't get get the piping right to do what i am trying to do:
split string into char array
turn each char into hex
wrap each hex value into %<FF>
concat string
this is my current way which gets me half way there:
echo -n "AaAa" | od -A n -t x1
If you are already using od,
printf "%%<%s>" $(od -A n -t x1<<<"AaAa")
For an all-bash without od,
while read -r -N 1 c; do printf "%%<%02X>" "$( printf "%d" \'$c )"; done <<< AaAa
The downside of this approach is that it spawns a subshell for every character, and assumes ASCII/UTF8.
edit
#Shawn pointed out that you don't need the subshell -
while read -r -N 1 c; do printf "%%<%02X>" \'$c; done <<< AaAa
I noticed that these are leaving the string terminator in your output, though, and realized I could eliminate that and the read by assigning the data to a variable and using the built-in parsing tools.
$: x=AaAa && for((i=0;i<${#x};i++)); do printf "%%<%02X>" \'${x:i:1}; done; echo
%<41>%<61>%<41>%<61>
A simple Perl substitution would do the trick:
echo -n AaAa | perl -pe's/(.)/ sprintf "%%<%02X>", ord($1) /seg'
Shorter:
echo -n AaAa | perl -ne'printf "%%<%02X>", $_ for unpack "C*"'
In both cases, the output is the expected
%<41>%<61>%<41>%<61>
(No trailing line feed added. If you want one, append ; END { print "\n" }.)
You can pipe to sed to wrap each byte in %<> and then remove the whitespace.
echo -n "AaAa" | od -A n -t x1 | sed -E -e 's/[a-z0-9]+/%<&>/g' -e 's/ //g'
You could use perl:
echo -n AaAa | perl -ne 'for $c (split//) { printf("%%<%02X>", ord($c)); }'
Output
%<41>%<61>%<41>%<61>
Maybe awk
echo -n "AaAa" |
od -A n -t x1 |
awk 'BEGIN { ORS = "" } { for (i = 1; i <= NF; i+=1) print "%<"$i">"}'
I have a code snippet that looks like this
while grep "{{SECRETS}}" /tmp/kubernetes/$basefile | grep -v "#"; do
grep -n "{{SECRETS}}" /tmp/kubernetes/$basefile | grep -v "#" | head -n1 | while read -r line ; do
lineno=$(echo $line | cut -d':' -f1)
spaces=$(sed "${lineno}!d" /tmp/kubernetes/$basefile | awk -F'[^ \t]' '{print length($1)}')
spaces=$((spaces-1))
# Delete line that had {{SECRETS}}
sed -i -e "${lineno}d" /tmp/kubernetes/$basefile
while IFS='' read -r secretline || [[ -n "$secretline" ]]; do
newline=$(printf "%*s%s" $spaces "" "$secretline")
sed -i "${lineno}i\ ${newline}" /tmp/kubernetes/$basefile
lineno=$((lineno+1))
done < "/tmp/secrets.yaml"
done
done
in /tmp/kubernetes/$basefile, the string {{SECRETS}} appears twice 100% of the time.
Almost every single time, this completes fine. However, very infrequently, the script errors on its second loop through the file. like so, according to set -x
...
IFS=
+ read -r secretline
+ [[ -n '' ]]
+ read -r line
exit code 1
When it works, the set -x looks like this, and continues processesing the file correctly.
...
+ IFS=
+ read -r secretline
+ [[ -n '' ]]
+ read -r line
+ grep '{{SECRETS}}' /tmp/kubernetes/deployment.yaml
+ grep -v '#'
I have no answer for how this can only happen occasionally, so I think there's something about bash piping's parallelism I don't understand. Is there something in grep -n "{{SECRETS}}" /tmp/kubernetes/$basefile | grep -v "#" | head -n1 | while read -r line ; do that could lead to out-of-order execution somehow? Based on the error, it seems like it's trying to read a line, but can't because previous commands didn't work. But there's no indication of that in the set -x output.
A likely cause of the problem is that the pipeline containing the inner loop both reads and writes the "basefile" at the same time. See How to make reading and writing the same file in the same pipeline always “fail”?.
One way to fix the problem is do a full read of the file before trying to update it. Try:
basepath=/tmp/kubernetes/$basefile
secretspath=/tmp/secrets.yaml
while
line=$(grep -n "{{SECRETS}}" "$basepath" | grep -v "#" | head -n1)
[[ -n $line ]]
do
lineno=$(echo "$line" | cut -d':' -f1)
spaces=$(sed "${lineno}!d" "$basepath" \
| awk -F'[^ \t]' '{print length($1)}')
spaces=$((spaces-1))
# Delete line that had {{SECRETS}}
sed -i -e "${lineno}d" "$basepath"
while IFS='' read -r secretline || [[ -n "$secretline" ]]; do
newline=$(printf "%*s%s" $spaces "" "$secretline")
sed -i "${lineno}i\ ${newline}" "$basepath"
lineno=$((lineno+1))
done < "$secretspath"
done
(I introduced the variables basepath and secretspath to make the code easier to test.)
As an aside, it's also possible to do this with pure Bash code:
basepath=/tmp/kubernetes/$basefile
secretspath=/tmp/secrets.yaml
updated_lines=()
is_updated=0
while IFS= read -r line || [[ -n $line ]] ; do
if [[ $line == *'{{SECRETS}}'* && $line != *'#'* ]] ; then
spaces=${line%%[^[:space:]]*}
while IFS= read -r secretline || [[ -n $secretline ]]; do
updated_lines+=( "${spaces}${secretline}" )
done < "$secretspath"
is_updated=1
else
updated_lines+=( "$line" )
fi
done <"$basepath"
(( is_updated )) && printf '%s\n' "${updated_lines[#]}" >"$basepath"
The whole updated file is stored in memory (in the update_lines array) but that shouldn't be a problem because any file that's too big to store in memory will almost certainly be too big to process line-by-line with Bash. Bash is generally extremely slow.
In this code spaces holds the actual space characters for indentation, not the number of them.
I have a file with lines. I want to reverse the words, but keep them in same order.
For example: "Test this word"
Result: "tseT siht drow"
I'm using MAC, so awk doesn't seem to work.
What I got for now
input=FILE_PATH
while IFS= read -r line || [[ -n $line ]]
do
echo $line | rev
done < "$input"
Here is a solution that completely avoids awk
#!/bin/bash
input=./data
while read -r line ; do
for word in $line ; do
output=`echo $word | rev`
printf "%s " $output
done
printf "\n"
done < "$input"
In case xargs works on mac:
echo "Test this word" | xargs -n 1 | rev | xargs
Inside your read loop, you can just iterate over the words of your string and pass them to rev
line="Test this word"
for word in "$line"; do
echo -n " $word" | rev
done
echo # Add final newline
output
tseT siht drow
You are actually in fairly good shape with bash. You can use string-indexes and string-length and C-style for loops to loop over the characters in each word building a reversed string to output. You can control formatting in a number of ways to handle spaces between words, but a simple flag first=1 is about as easy as anything else. You can do the following with your read,
#!/bin/bash
while read -r line || [[ -n $line ]]; do ## read line
first=1 ## flag to control space
a=( $( echo $line ) ) ## put line in array
for i in "${a[#]}"; do ## for each word
tmp= ## clear temp
len=${#i} ## get length
for ((j = 0; j < len; j++)); do ## loop length times
tmp="${tmp}${i:$((len-j-1)):1}" ## add char len - j to tmp
done
if [ "$first" -eq '1' ]; then ## if first word
printf "$tmp"; first=0; ## output w/o space
else
printf " $tmp" ## output w/space
fi
done
echo "" ## output newline
done
Example Input
$ cat dat/lines2rev.txt
my dog has fleas
the cat has none
Example Use/Output
$ bash revlines.sh <dat/lines2rev.txt
ym god sah saelf
eht tac sah enon
Look things over and let me know if you have questions.
Using rev and awk
Consider this as the sample input file:
$ cat file
Test this word
Keep the order
Try:
$ rev <file | awk '{for (i=NF; i>=2; i--) printf "%s%s",$i,OFS; print $1}'
tseT siht drow
peeK eht redro
(This uses awk but, because it uses no advanced awk features, it should work on MacOS.)
Using in a script
If you need to put the above in a script, then create a file like:
$ cat script
#!/bin/bash
input="/Users/Anastasiia/Desktop/Tasks/test.txt"
rev <"$input" | awk '{for (i=NF; i>=2; i--) printf "%s%s",$i,OFS; print $1}'
And, run the file:
$ bash script
tseT siht drow
peeK eht redro
Using bash
while read -a arr
do
x=" "
for ((i=0; i<${#arr}; i++))
do
((i == ${#arr}-1)) && x=$'\n'
printf "%s%s" $(rev <<<"${arr[i]}") "$x"
done
done <file
Applying the above to our same test file:
$ while read -a arr; do x=" "; for ((i=0; i<${#arr}; i++)); do ((i == ${#arr}-1)) && x=$'\n'; printf "%s%s" $(rev <<<"${arr[i]}") "$x"; done; done <file
tseT siht drow
peeK eht redro
I have a SQL*Plus output written into a text file in the following format:
3459906| |2|X1|WAS1| Output1
334596| |2|X1|WAS2| Output1
3495792| |1|X1|WAS1| Output1
687954| |1|X1|WAS2| Output1
I need a shell script to fetch the counts which were at the beginning based on the text after the counts.
For example, If the Text is like |2|X1|WAS1| , then 3459906 should be passed on to a variable x1was12 and if the text is like |2|X1|WAS2| , then 334596 should be passed on to a variable x1was22.
I tried writing a for loop and if condition to pass on the counts, but was unsuccessful:
export filename1='file1.dat'
while read -r line ; do
if [[ grep -i "*|2|X1|WAS1| Output1*" | wc -l -eq 0 ]] ; then
export xwas12=sed -n ${line}p $filename1 | \
sed 's/[^0-9]*//g' | sed 's/..$//'
elif [[ grep -i "*|2|X1|WAS2| Output1*" | wc -l -eq 0 ]] ; then
export x1was22=sed -n ${line}p $filename1 | \
sed 's/[^0-9]*//g' | sed 's/..$//'
elif [[ grep -i "*|1|X1|WAS1| Output1*" | wc -l -eq 0 ]] ; then
export x1was11=sed -n ${line}p $filename1 | \
sed 's/[^0-9]*//g' | sed 's/..$//'
elif [[ grep -i "*|1|X1|WAS2| Output1*" | wc -l -eq 0 ]]
export x1was21=sed -n ${line}p $filename1 | \
sed 's/[^0-9]*//g' | sed 's/..$//'
fi
done < "$filename1"
echo '$x1was12' > output.txt
echo '$x1was22' >> output.txt
echo '$x1was11' >> output.txt
echo '$x1was21' >> output.txt
What I was trying to do was:
Go to the first line in the file
-> Search for the text and if found then assign the sed output to the variable
Then go to the second line of the file
-> Search for the texts in the if commands and assign the sed output to another variable.
same goes for other
while IFS='|' read -r count _ n x was _; do
# remove spaces from all variables
count=${count// /}; n=${n// /}; x=${x// /}; was=${was// /}
varname="${x}${was}${n}"
printf -v "${varname,,}" %s "$count"
done <<'EOF'
3459906| |2|X1|WAS1| Output1
334596| |2|X1|WAS2| Output1
3495792| |1|X1|WAS1| Output1
687954| |1|X1|WAS2| Output1
EOF
With the above executed:
$ echo "$x1was12"
3459906
Of course, the redirection from a heredoc could be replaced with a redirection from a file as well.
How does this work? Let's break it down:
Every time IFS='|' read -r count _ n x was _ is run, it reads a single line, separating it by |s, putting the first column into count, discarding the second by assigning it to _, reading the third into n, the fourth into x, the fifth into was, and the sixth and all following content into _. This practice is discussed in detail in BashFAQ #1.
count=${count// /} is a parameter expansion which prunes spaces from the variable count, by replacing all such spaces with empty strings. See also BashFAQ #100.
"${varname,,}" is another parameter expansion, this one converting a variable's contents to all-lowercase. (This requires bash 4.0; in prior versions, consider "$(tr '[:upper:]' '[:lower:]' <<<"$varname") as a less-efficient alternative).
printf -v "$varname" %s "value" is a mechanism for doing an indirect assignment to the variable named in the variable varname.
If not for the variable names, the whole thing could be done with two commands:
cut -d '|' -f1 file1.dat | tr -d ' ' > output.txt
The variable names make it more interesting. Two bash methods follow, plus a POSIX method...
The following bash code ought to do what the OP's sample code was
meant to do:
declare $(while IFS='|' read a b c d e f ; do
echo $a 1>&2 ; echo x1${e,,}$c=${a/ /}
done < file1.dat 2> output.txt )
Notes:
The bash shell is needed for ${e,,}, (turns "WAS" into "was"), and $a/ /} , (removes a leading space that might be in
$a), and declare.
The while loop parses file1.dat and outputs a bunch of variable assignments. Without the declare this code:
while IFS='|' read a b c d e f ; do
echo x1${e,,}$c=${a/ /} ;
done < file1.dat
Outputs:
x1was12=3459906
x1was22=334596
x1was11=3495792
x1was21=687954
The while loop outputs to two separate streams: stdout (for the declare), and stderr (using the 1>&2 and 2> redirects for
output.txt).
Using bash associative arrays:
declare -A x1was="( $(while IFS='|' read a b c d e f ; do
echo $a 1>&2 ; echo [${e/WAS/}$c]=${a/ /}
done < file1.dat 2> output.txt ) )"
In which case the variable names require brackets:
echo ${x1was[21]}
687954
POSIX shell code (tested using dash):
eval $(while IFS='|' read a b c d e f ; do
echo $a 1>&2; echo x1$(echo $e | tr '[A-Z]' '[a-z]')$c=$(echo $a)
done < file1.dat 2> output.txt )
eval should not be used if there's any doubt about what's in file1.dat. The above code assumes the data in file1.dat is
uniformly dependable.