I try to add a number at the end of each line for each files in a dir and update it.
Let's say: starting with 1 for the first file, 2 for the second file and so on.
The script I used is as follow:
#!/bin/bash
n=1
for filename in $HOME/path/to/direc/*
do
sed -i 's/$/ $(($n + 1))/g' $filename
done
The command I tough naively works like that: add a space and a number at the end of each line of file $filename. The number is updated each time with the condition $(($n + 1)).
Instead it print out at the end of each line of each file: " $(($n + 1))" ...
The 'space', at the beginning it's ok, but not the number.
Many thanks.
Bash doesn't interpolate strings in single quotes. Try double quotes instead.
Also, the /g is not needed, as $ can only match once per line.
To update the variable value, you need to assign the new value to it
$(( n = n + 1 ))
or, shorter
$(( n += 1 ))
or, even shorter
$(( n++ ))
Related
How to do arithmetic with floating point numbers such as 1.503923 in a shell script? The floating point numbers are pulled from a file as a string. The format of the file is as follows:
1.5493482,3.49384,33.284732,23.043852,2.2384...
3.384,3.282342,23.043852,2.23284,8.39283...
.
.
.
Here is some simplified sample code I need to get working. Everything works fine up to the arithmetic. I pull a line from the file, then pull multiple values from that line. I think this would cut down on search processing time as these files are huge.
# set vars, loops etc.
while [ $line_no -gt 0 ]
do
line_string=`sed -n $line_no'p' $file_path` # Pull Line (str) from a file
string1=${line_string:9:6} # Pull value from the Line
string2=${line_string:16:6}
string3=...
.
.
.
calc1= `expr $string2 - $string7` |bc -l # I tried these and various
calc2= ` "$string3" * "$string2" ` |bc -l # other combinations
calc3= `expr $string2 - $string1`
calc4= "$string2 + $string8" |bc
.
.
.
generic_function_call # Use the variables in functions
line_no=`expr $line_no - 1` # Counter--
done
Output I keep getting:
expr: non-numeric argument
command not found
I believe you should use : bc
For example:
echo "scale = 10; 123.456789/345.345345" | bc
(It's the unix way: each tool specializes to do well what they are supposed to do, and they all work together to do great things. don't emulate a great tool with another, make them work together.)
Output:
.3574879198
Or with a scale of 1 instead of 10:
echo "scale = 1; 123.456789/345.345345" | bc
Output:
.3
Note that this does not perform rounding.
I highly recommand switching to awk if you need to do more complex operations, or perl for the most complex ones.
ex: your operations done with awk:
# create the test file:
printf '1.5493482,3.49384,33.284732,23.043852,2.2384,12.1,13.4,...\n' > somefile
printf '3.384,3.282342,23.043852,2.23284,8.39283,14.1,15.2,...\n' >> somefile
# do OP's calculations (and DEBUG print them out!)
awk -F',' '
# put no single quote in here... even in comments! you can instead print a: \047
# the -F tell awk to use "," as a separator. Thus awk will automatically split lines for us using it.
# $1=before first "," $2=between 1st and 2nd "," ... etc.
function some_awk_function_here_if_you_want() { # optionnal function definition
# some actions here. you can even have arguments to the function, etc.
print "DEBUG: no action defined in some_awk_function_here_if_you_want yet ..."
}
BEGIN { rem="Optionnal START section. here you can put initialisations, that happens before the FIRST file-s FIRST line is read"
}
(NF>=8) { rem="for each line with at least 8 values separated by commas (and only for lines meeting that condition)"
calc1=($2 - $7)
calc2=($3 * $2)
calc3=($2 - $1)
calc4=($2 + $8)
# uncomment to call this function :(ex1): # some_awk_function_here_if_you_want
# uncomment to call this script:(ex2): # cmd="/path/to/some/script.sh \"" calc1 "\" \"" calc2 "\" ..." ; rem="continued next line"
# uncomment to call this script:(ex2): # system(cmd); close(cmd)
line_no=(FNR-1) # ? why -1? . FNR=line number in the CURRENT file. NR=line number since the beginning (NR>FNR after the first file ...)
print "DEBUG: calc1=" calc1 " , calc2=" calc2 " , calc3=" calc3 " , calc4=" calc4 " , line_no=" line_no
print "DEBUG fancier_exemples: see man printf for lots of info on formatting (%...f for floats, %...d for integer, %...s for strings, etc)"
printf("DEBUG: calc1=%d , calc2=%10.2f , calc3=%s , calc4=%d , line_no=%d\n",calc1, calc2, calc3, calc4, line_no)
}
END { rem="Optionnal END section. here you can put things that need to happen AFTER the LAST file-s LAST line is read"
}
' somefile # end of the awk script, and the list of file(s) to be read by it.
What about this?
calc=$(echo "$String2 + $String8"|bc)
This will make bc to add the values of $String2 and $String8 and saves the result in the variable calc.
If you don't have the "bc" you can just use 'awk' :
calc=$(echo 2.3 4.6 | awk '{ printf "%f", $1 + $2 }')
scale in bc is the precission so with a scale of 4 if you type bc <<< 'scale=4;22.0/7' you get 3.1428 as an answer. If you use a scale of 8 you get 3.14285714 which is 8 numbers after the floating point.
So the scale is a precission factor
I'm a bit stuck with something. I have a for loop like this:
#!/bin/bash
for i in {10..15}
do
I want to obtain the last digit of the number, so if i is 12, I want to get 2. I'm having difficulties with the syntax though. I've read that I should convert it into a character array, but when I do something like:
j=${i[#]}
echo $j
I don't get 1 0 1 1 1 2 and so on...I get 10, 11, 12...How do I get the numbers to be split up so I can get the last one of i, when I don't always know how many digits will make up i (ex. it may be 1, or 10, or a 100, etc.)?
Trick is to treat $i like a string.
for i in {10..15}; do j="${i: -1}"; echo $j; done
Of course, you do not need to assign to a variable if you don't want to:
for i in {10..15}; do echo "${i: -1}"; done
This answer which uses GNU shell parameter expansion is the most sensible method, I guess.
However, you can also use the double parenthesis construct which allows C-style manipulation of variables in Bash.
for i in {10..15}
do
(( j = i % 10 )) # modulo 10 always gives the ones' digit
echo $j
done
This awk command could solve your problem:
awk '{print substr($0,length,1)}' test_file
I'm assuming that the numbers are saved in a file test_file
If you want to use for loop:
for i in `cat test_1`
do
echo $i |tail -c 2
done
I am trying to create a Bash script that
- prints a random word
- if a number is supplied as the first command line argument then it will select from only words with that many characters.
This is my go at the first section (print a random word):
C=$(sed -n "$RANDOM p" /usr/share/dict/words)
echo $C
I am really stuck with the second section. Can anyone help?
might help someone coming from ryans tutorial
#!/bin/bash
charlen=$1
grep -E "^.{$charlen}$" $PWD/words.txt | shuf -n 1
you have to use a while loop to read every single line of that file and check if the length of a word equals the specified number ( including apostrophes ). In my o.s it is 99171 line ( i.e the file).
#!/usr/bin/env bash
readWords() {
declare -i int="$1"
(( int == 0 )) && {
printf "%s\n" "$int is 0, cant find 0 words"
return 1
}
while read getWords;do
if [[ ${#getWords} -eq $int ]];then
printf "%s\n" "$getWords"
fi
done < /usr/share/dict/words
}
readWords 20
this function takes a single argument. the declare command coerces the argument into an integer, if the argument is a string , it coerces it into a number which is 0 . Since we don't have 0 words if the specified argument ( number ) is 0 ( or a string coerced to 0 ) return from the function.
Read every single line in /usr/share/dict/words, get the length of each line with ${#getWords} ( $# >> gives the length of a string/commandline parameters/array size ) check if it equals the specified argument ( number )
A loop is not required, you can do something like
CH=$1; # how many characters the word must have
WordFile=/usr/share/dict/words; # file to read from
# find how many words that matches that length
TOTW=$(grep -Ec "^.{$CH}$" $WordFile);
# pick a random one, if you expect more than 32767 hits you
# need to do something like ($RANDOM+1)*($RANDOM+1)
RWORD=$(($RANDOM%$TOTW+1));
#show that word
grep -E "^.{$CH}$" $WordFile|sed -n "$RWORD p"
Depending on things you probably need to add checks for things like that $1 is a reasonable number, the file exist, that TOTW is >0 and so on.
This code would achieve what you want:
awk -v n="$1" 'length($0) == n' /usr/share/dict/words > /tmp/wordsHolder
shuf -n 1 /tmp/wordsHolder
Some comments: by using "$RANDOM" (as you did on your original script attempt), one would generate an integer on the range 0 - 32767, which could be more (or less) than the number of words (lines) available, given the desired number of characters on a word -- thus, potential for errors here.
To avoid that, we are using a shuf syntax that will retrieve a (sub)randomly picked word (line) on the file using its entire range (from line 1 - last line of file).
How to do arithmetic with floating point numbers such as 1.503923 in a shell script? The floating point numbers are pulled from a file as a string. The format of the file is as follows:
1.5493482,3.49384,33.284732,23.043852,2.2384...
3.384,3.282342,23.043852,2.23284,8.39283...
.
.
.
Here is some simplified sample code I need to get working. Everything works fine up to the arithmetic. I pull a line from the file, then pull multiple values from that line. I think this would cut down on search processing time as these files are huge.
# set vars, loops etc.
while [ $line_no -gt 0 ]
do
line_string=`sed -n $line_no'p' $file_path` # Pull Line (str) from a file
string1=${line_string:9:6} # Pull value from the Line
string2=${line_string:16:6}
string3=...
.
.
.
calc1= `expr $string2 - $string7` |bc -l # I tried these and various
calc2= ` "$string3" * "$string2" ` |bc -l # other combinations
calc3= `expr $string2 - $string1`
calc4= "$string2 + $string8" |bc
.
.
.
generic_function_call # Use the variables in functions
line_no=`expr $line_no - 1` # Counter--
done
Output I keep getting:
expr: non-numeric argument
command not found
I believe you should use : bc
For example:
echo "scale = 10; 123.456789/345.345345" | bc
(It's the unix way: each tool specializes to do well what they are supposed to do, and they all work together to do great things. don't emulate a great tool with another, make them work together.)
Output:
.3574879198
Or with a scale of 1 instead of 10:
echo "scale = 1; 123.456789/345.345345" | bc
Output:
.3
Note that this does not perform rounding.
I highly recommand switching to awk if you need to do more complex operations, or perl for the most complex ones.
ex: your operations done with awk:
# create the test file:
printf '1.5493482,3.49384,33.284732,23.043852,2.2384,12.1,13.4,...\n' > somefile
printf '3.384,3.282342,23.043852,2.23284,8.39283,14.1,15.2,...\n' >> somefile
# do OP's calculations (and DEBUG print them out!)
awk -F',' '
# put no single quote in here... even in comments! you can instead print a: \047
# the -F tell awk to use "," as a separator. Thus awk will automatically split lines for us using it.
# $1=before first "," $2=between 1st and 2nd "," ... etc.
function some_awk_function_here_if_you_want() { # optionnal function definition
# some actions here. you can even have arguments to the function, etc.
print "DEBUG: no action defined in some_awk_function_here_if_you_want yet ..."
}
BEGIN { rem="Optionnal START section. here you can put initialisations, that happens before the FIRST file-s FIRST line is read"
}
(NF>=8) { rem="for each line with at least 8 values separated by commas (and only for lines meeting that condition)"
calc1=($2 - $7)
calc2=($3 * $2)
calc3=($2 - $1)
calc4=($2 + $8)
# uncomment to call this function :(ex1): # some_awk_function_here_if_you_want
# uncomment to call this script:(ex2): # cmd="/path/to/some/script.sh \"" calc1 "\" \"" calc2 "\" ..." ; rem="continued next line"
# uncomment to call this script:(ex2): # system(cmd); close(cmd)
line_no=(FNR-1) # ? why -1? . FNR=line number in the CURRENT file. NR=line number since the beginning (NR>FNR after the first file ...)
print "DEBUG: calc1=" calc1 " , calc2=" calc2 " , calc3=" calc3 " , calc4=" calc4 " , line_no=" line_no
print "DEBUG fancier_exemples: see man printf for lots of info on formatting (%...f for floats, %...d for integer, %...s for strings, etc)"
printf("DEBUG: calc1=%d , calc2=%10.2f , calc3=%s , calc4=%d , line_no=%d\n",calc1, calc2, calc3, calc4, line_no)
}
END { rem="Optionnal END section. here you can put things that need to happen AFTER the LAST file-s LAST line is read"
}
' somefile # end of the awk script, and the list of file(s) to be read by it.
What about this?
calc=$(echo "$String2 + $String8"|bc)
This will make bc to add the values of $String2 and $String8 and saves the result in the variable calc.
If you don't have the "bc" you can just use 'awk' :
calc=$(echo 2.3 4.6 | awk '{ printf "%f", $1 + $2 }')
scale in bc is the precission so with a scale of 4 if you type bc <<< 'scale=4;22.0/7' you get 3.1428 as an answer. If you use a scale of 8 you get 3.14285714 which is 8 numbers after the floating point.
So the scale is a precission factor
I am making a shell script that takes a single number (length is unimportant) from the command line and adds the digits of it together. I thought I had it, but it won't work and either displays "0+3+4+5" if the command input is 345 or it displays the variables when I use expr to add them.
#!/bin/bash
sum=0
i="$(expr length $1)"
s=$1
for i in $(seq 0 $((${#s} - 1))); do
value=${s:$i:1}
typeset -i value
sum=$sum+$value
done
echo $sum
Also doesn't work when I replace it with sum='expr $sum + $value'
any ideas?
What you are looking for is sum=$(($sum+$value)).
#!/bin/bash
expr $(echo $1| sed 's/./& + /g;s/..$//')
For example, if the argument is 12345, this translates it to the string 1 + 2 + 3 + 4 + 5 and uses expr to evaluate it.