Start doing it. You only get the experience when you actually do the work. Theory is nice to have but you really only learn how to do things when you're actually doing them. My first scripts were pretty shitty, I didn't know any better. Experience has taught me that there are sometimes better ways of solving a specific problem. That's something you have to find out.
Start doing it, then you'll run into those implementation details. For the most part you don't need to worry about it.
This is a good place to start: https://www.grymoire.com/Unix/Sh.html
Arrays are a typical bash construct. Stick to standard POSIX shell. If you can't hack it with a shell script use Python or some other, more advanced, scripting language. Or, if you insist on using bash specifics, install shells/bash. Don't assume that a bash(1) script will always run on sh(1).
find /usr/ports/clean_backup -name Makefile -exec grep "PKGNAMEPREFIX=" {} "+" | grep -w "qt5-" | cut -d/ -f5-6 | grep -v py-qt5 >> all_qt5_ports.txtgreps work on the Makefile. But the last grep needs to work on the entire command's output before tacking it onto the end of all_qt5_ports.txt.Yes, this times infinity or divide by zero. Shells are "language". Languages are best learn by doing, even spoken language. Start out with Hello World! and then get more complex.
let's say instead of writing to the array i'll just print it out on the screen. It's the first defference in bash and you told me about, great not I know 1 more not only that this is just sh and bash in first line. Thank you
)
Something really simple:
dice@armitage:~/test % cat sometext.txt
This is some text
spread over multiple lines
Hello World!
dice@armitage:~/test % cat read.sh
#!/bin/sh
while read LINE; do
echo $LINE
done < sometext.txt
dice@armitage:~/test % ./read.sh
This is some text
spread over multiple lines
Hello World!
#!/bin/sh
IFS="
"
i=0
while read line
do
eval VAR_$i=\"$line\"
i=$(($i+1))
done
j=0
while [ $j -lt $i ]
do
eval line="\$VAR_$j"
echo $j "=>" $line
j=$(($j+1))
done0 => # : releng/12.2/bin/sh/profile 363525 2020-07-25 11:57:39Z pstef $
1 => #
2 => # System-wide .profile file for sh(1).
3 => #
4 => # For the setting of languages and character sets please see
5 => # login.conf(5) and in particular the charset and lang options.
6 => # For full locales list check /usr/share/locale/*
7 => # You should also read the setlocale(3) man page for information
8 => # on how to achieve more precise control of locale settings.
9 => #
10 => # Check system messages
11 => # msgs -q
12 => # Allow terminal messages
13 => # mesg yIt wont help in the case when the environment wont allow me to install php or perl, and as far as I know Perl now is the part of Linux, I really wan't to have comfort wiht shells, couse I think one time I won't be able to use something else.You didn't ask for it but i think looking into scripting languages like Perl or Python would be worth a try.
You can create very sophisticated programs with them. (And they do have arrays
It's not, and it never was. I've done a lot of Perl coding (lang/perl5.32) in the past but nowadays I would use lang/python38 instead.
In addition to this reference, when you need a standard aproach for (more elaborate) argument processing with sh(1) getops: Shell Scripts 2: Script utilities. Have a look at part 1 as well: Shell Scripts 1: Bourne back again, also by Steve Tarver.
Do not use bash(1) for script. Use POSIX /bin/sh which works everywhere and is portable.
vermaden.wordpress.com
#!/bin/sh
# i: counter
# j: counter
# a: array
# l: line
# v: value
# read and write to an array!
i=0
while IFS= read l; do
eval a_${i}=\$l
i=`expr $i + 1`
done < "$1"
# print the array
j=0
while [ $j -lt $i ]; do
eval v=\$a_${j}
j=$((j + 1))
printf "%*u: %s\n" "${#i}" $j $v
donefile1.txt
file2.txt
.
.
.
fileN.txt $ chmod u+x scriptFile $ ./scriptFile textFile1: file1.txt
2: file2.txt
.
.
.
N: fileN.txtyou can quickly access them by the index so it's as close to an array as it gets
awk to simulate array-like structures in sh(1) -- a simple example:
#!/bin/sh
list="a b c d e foo g"
listcount=$(echo $list | awk 'BEGIN{FS=" "}{print NF}')
echo 'List="'$list'"'
echo "Element count="$listcount
echo "A random element access:"
el=$(echo $list | awk 'BEGIN{FS=" "}{print $6}')
echo "Element 6 = "$el
echo "Iteration:"
i=0; for x in $list; do
i=$(($i+1))
echo "Element "$i" = "$(echo $list | awk 'BEGIN{FS=" "}{print $'$i'}')
done