I need to write values to a particular column in a text file, say 10th column.
touch test.txt
echo "232" >> test.txt # I want 232 to start from 10th column of text file
How to go about ?
printf is another alternative to provide an offset. It has the advantage of being able to take the amount of offset (field width) as an argument to the format specifier. The following will take the column offset as the first argument and the data to write at that offset as the second argument (your defaults of 10/232 are used) for example:
#!/bin/sh
col="${1:-10}" # column offset (default: 10)
stuff="${2:-232}" # variable to write at offset
printf "%*s%s\n" "$col" "" "$stuff" # write $stuff at $col offset
exit 0
To create the offset, the printf command format specifier just says use a minimum field width of $col to write the empty-string ("") and thereafter write your data (in $stuff) followed by a newline. With the script saved as prncol.sh:
output:
$ bash prncol.sh
232
$ bash prncol.sh 5 501
501
$ bash prncol.sh 15 anything
anything
Of course to write the output to test.txt, just redirect/append the output of printf to test.txt
for x in $(seq 10)
do
echo -n ' '
done
echo "232" >> test.txt
Related
I have a list of files with file names that contain a substring of 6 numbers that represents HHMMSS, HH: 2 digits hour, MM: 2 digits minutes, SS: 2 digits seconds.
If the list of files is ordered, the increments should be in steps of 30 minutes, that is, the first substring should be 000000, followed by 003000, 010000, 013000, ..., 233000.
I want to check that no file is missing iterating the list of files and checking that neither of these substrings is missing. My approach:
string_check=000000
for file in ${file_list[#]}; do
if [[ ${file:22:6} == $string_check ]]; then
echo "Ok"
else
echo "Problem: an hour (file) is missing"
exit 99
fi
string_check=$((string_check+3000)) #this is the key line
done
And the previous to the last line is the key. It should be formatted to 6 digits, I know how to do that, but I want to add time like a clock, or, in more specific words, modular arithmetic modulo 60. How can that be done?
Assumptions:
all 6-digit strings are of the format xx[03]0000 (ie, has to be an even 00 or 30 minutes and no seconds)
if there are strings like xx1529 ... these will be ignored (see 2nd half of answer - use of comm - to address OP's comment about these types of strings being an error)
Instead of trying to do a bunch of mod 60 math for the MM (minutes) portion of the string, we can use a sequence generator to generate all the desired strings:
$ for string_check in {00..23}{00,30}00; do echo $string_check; done
000000
003000
010000
013000
... snip ...
230000
233000
While OP should be able to add this to the current code, I'm thinking we might go one step further and look at pre-parsing all of the filenames, pulling the 6-digit strings into an associative array (ie, the 6-digit strings act as the indexes), eg:
unset myarray
declare -A myarray
for file in ${file_list}
do
myarray[${file:22:6}]+=" ${file}" # in case multiple files have same 6-digit string
done
Using the sequence generator as the driver of our logic, we can pull this together like such:
for string_check in {00..23}{00,30}00
do
[[ -z "${myarray[${string_check}]}" ]] &&
echo "Problem: (file) '${string_check}' is missing"
done
NOTE: OP can decide if the process should finish checking all strings or if it should exit on the first missing string (per OP's current code).
One idea for using comm to compare the 2 lists of strings:
# display sequence generated strings that do not exist in the array:
comm -23 <(printf "%s\n" {00..23}{00,30}00) <(printf "%s\n" "${!myarray[#]}" | sort)
# OP has commented that strings not like 'xx[03]000]` should generate an error;
# display strings (extracted from file names) that do not exist in the sequence
comm -13 <(printf "%s\n" {00..23}{00,30}00) <(printf "%s\n" "${!myarray[#]}" | sort)
Where:
comm -23 - display only the lines from the first 'file' that do not exist in the second 'file' (ie, missing sequences of the format xx[03]000)
comm -13 - display only the lines from the second 'file' that do not exist in the first 'file' (ie, filenames with strings not of the format xx[03]000)
These lists could then be used as input to a loop, or passed to xargs, for additional processing as needed; keeping in mind the comm -13 output will display the indices of the array, while the associated contents of the array will contain the name of the original file(s) from which the 6-digit string was derived.
Doing this easy with POSIX shell and only using built-ins:
#!/usr/bin/env sh
# Print an x for each glob matched file, and store result in string_check
string_check=$(printf '%.0sx' ./*[0-2][0-9][03]000*)
# Now string_check length reflects the number of matches
if [ ${#string_check} -eq 48 ]; then
echo "Ok"
else
echo "Problem: an hour (file) is missing"
exit 99
fi
Alternatively:
#!/usr/bin/env sh
if [ "$(printf '%.0sx' ./*[0-2][0-9][03]000*)" \
= 'xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx' ]; then
echo "Ok"
else
echo "Problem: an hour (file) is missing"
exit 99
fi
I have written a bash script that generates a CSV file. However, I now want to run a loop before I generate this CSV file and deduct certain value from each column.
Here is my code for better understanding:
for loop; do
$VAL /*global*/
file="./out_base.txt"
while IFS=' ' read -r f1 f2 f3
do
$VAL = $f2
done <"$file"
file="./out_lw.txt"
while IFS=' ' read -r f4 f5 f6
do
$((f4-VAL)) >> val_lw.csv
done <"$file"
done
out_base.txt is in format: a b c
out_lw.txt is in format: d e f
Desired output: val_lw.csv should look like:
b-e /*(where - is a mathematical minus operator)
e.g:
out_base.txt:
sim_ticks 32768 #number of ticks
sim_ticks 31111 #number of ticks
out_lw.txt:
sim_ticks 65433 #number of ticks
sim_ticks 74333 #number of ticks
intented val_lw.csv:
32665
43222
However, I am not able to perform the mathematical operation and get the desired results.
Corresponding Output: val_lw.csv is a blank file.
Can someone help me please ?
I think life would be easier with awk like this:
awk 'FNR==NR{x[FNR]=$2;next} {print x[FNR]-$2}' out_lw.csv out_base.csv > vl_lw.csv
32665
43222
Explanation:
Run awk on both files, out_lw.csv and out_base.csv. If reading the first file, save the second field in array x indexed by the line number FNR, then jump to the next line. If reading the second file, print the corresponding saved value from x minus the second field on the current line.
If you really want to use bash, it might look something like this:
#!/bin/bash
# Load all numbers from "out_base.txt" into array "base[]"
base=( $(cut -d ' ' -f2 out_base.txt ) )
# Iterate through "out_lw.txt"
line=0
while read a b c ; do
((diff=b-base[line]))
echo $diff
((line=line+1))
done < out_lw.txt
I'm trying to make a list with a simple bash looping
I want this:
000000
000001
000002
They give me this:
0
1
2
My shell code:
countBEG="000000"
countEND="999999"
while [ $countBEG != $countEND ]
do
echo "$countBEG"
countBEG=$[$countBEG +1]
done
Change your echo to use printf, where you can specify format for left padding.
printf "%06d\n" "$countBEG"
This sets 6 as fixed length of the output, using zeros to fill empty spaces.
You're looking for:
seq -w "$countBEG" "$countEND"
The -w option does the padding.
The following command will produce the desired output (no need for the loop) :
printf '%06d\n' {1..999999}
Explanation :
{1..999999} is expanded by bash to the sequence of 1 to 999999
the format string '%06d\n' tells printf to display the number it is given as argument padded to 6 digits and followed by a linefeed
printf repeats this output if it is given more arguments than is defined in its format specification
I am trying to create a Bash script that
- prints a random word
- if a number is supplied as the first command line argument then it will select from only words with that many characters.
This is my go at the first section (print a random word):
C=$(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 do I compare current timestamp and a field of a file and print the matched and unmatched data. I have 2 columns in a file (see below)
oac.bat 09:09
klm.txt 9:00
I want to compare the timestamp(2nd column) with current time say suppose(10:00) and print the output as follows.
At 10:00
greater.txt
xyz.txt 10:32
mnp.csv 23:54
Lesser.txt
oac.bat 09:09
klm.txt 9:00
Could anyone help me on this please ?
I used awk $0 > "10:00", which gives me only 2nd column details but I want both the column details and I am taking timestamp from system directly from system with a variable like
d=`date +%H:%M`
With GNU awk you can just use it's builtin time functions:
awk 'BEGIN{now = strftime("%H:%M")} {
split($NF,t,/:/)
cur=sprintf("%02d:%02d",t[1],t[2])
print > ((cur > now ? "greater" : "lesser") ".txt")
}' file
With other awks just set now using -v and date up front, e.g.:
awk -v now="$(date +"%H:%M")" '{
split($NF,t,/:/)
cur = sprintf("%02d:%02d",t[1],t[2])
print > ((cur > now ? "greater" : "lesser") ".txt")
}' file
The above is untested since you didn't provide input/output we could test against.
Pure Bash
The script can be implemented in pure Bash with the help of date command:
# Current Unix timestamp
let cmp_seconds=$(date +%s)
# Read file line by line
while IFS= read -r line; do
let line_seconds=$(date -d "${line##* }" +%s) || continue
(( line_seconds <= cmp_seconds )) && \
outfile=lesser || outfile=greater
# Append the line to the file chosen above
printf "%s\n" "$line" >> "${outfile}.txt"
done < file
In this script, ${line##* } removes the longest match of '* ' (any character followed by a space) pattern from the front of $line thus fetching the last column (the time). The time column is supposed to be in one of the following formats: HH:MM, or H:MM. Actually, date's -d option argument
can be in almost any common format. It can contain month names, time zones, ‘am’ and ‘pm’, ‘yesterday’, etc.
We use the flexibility of this option to convert the time (HH:MM, or H:MM) to Unix timestamp.
The let builtin allows arithmetic to be performed on shell variables. If the last let expression fails, or evaluates to zero, let returns 1 (error code), otherwise 0 (success). Thus, if for some reason the time column is in invalid format, the iteration for such line will be skipped with the help of continue.
Perl
Here is a Perl version I have written just for fun. You may use it instead of the Bash version, if you like.
# For current date
#cmp_seconds=$(date +%s)
# For specific hours and minutes
cmp_seconds=$(date -d '10:05' +%s)
perl -e '
my #t = localtime('$cmp_seconds');
my $minutes = $t[2] * 60 + $t[1];
while (<>) {
/ (\d?\d):(\d\d)$/ or next;
my $fh = ($1 * 60 + $2) > $minutes ? STDOUT : STDERR;
printf $fh "%s", $_;
}' < file >greater.txt 2>lesser.txt
The script computes the number of minutes in the following way:
HH:MM = HH * 60 + MM minutes
If the number of minutes from the file are greater then the number of minutes for the current time, it prints the next line to the standard output, otherwise to standard error. Finally, the standard output is redirected to greater.txt, and the standard error is redirected to lesser.txt.
I have written this script for demonstration of another approach (algorithm), which can be implemented in different languages, including Bash.