i am searching in google but i can.t find that.i want a Successful shell script and using for loop.most of the case fails for searching this things.enter image description here
You can two scripts:
1. Server List, this can contain a list of destination hostnames each one on a new line.
2. A copy script, which can basically cat the above server list and then execute scp command to copy the file for the same. It can also accept parameters if your server list is different per every application. Below is a sample:
Usage()
{
echo "Usage: $0 [-a application] [-l level]"
echo " where application = {a, b, c , d }"
exit 1;
}
SERVER_LIST=a.txt
for HOST in `cat $SERVER_LIST | grep -v ^# | cut -d: -f2`
do
spawn /usr/bin/scp FILE user#$HOST:destinationDirectory
expect {
"*password:*" { send $PASSWORD\r;interact }
}
exit
"
done
I have a script written and I want to include a function in the script, that silently logs the console output to a .txt file. The printf used in my shell scripts have colors for certain characters.
A sample:
# Color block
G="\033[32m"
N="\033[0m"
R="\033[31m"
Y="\033[33m"
# MCS Check
mcs=$(cat /home/admin/service-health.txt | grep -i mcs | cut -d ' ' -f 5 | tr . " ")
if [ "$mcs" == "up " ]
then
printf "${Y}MCS${N} Service Status is\t\t |${G}UP${N}\n"
else
printf "${Y}MCS${N} Service Status is\t\t |${R}DOWN${N}\n"
fi
Console output for this will display the color.
This is not mandatory in the .txt logging.
I will then be emailing this .txt to an address using:
sendmail $vdp $eaddr < /home/admin/health-check.txt
I used this block as I want to redirect the output within the script itself:
sudo touch /home/admin/health-check.txt
exec > >(tee -i /home/admin/health-check.txt)
exec 2>&1
But since this is a colored output, I keep getting this in my email:
[33mGSAN[0m Service Status is |[32mUP[0m
[33mMCS[0m Service Status is |[32mUP[0m
[33mTomcat[0m Service Status is |[32mUP[0m
[33mScheduler[0m Service Status is |[32mUP[0m
[33mMaintenance[0m Service Status is |[32mUP[0m
VDP [33mAccess State[0m is |[32mFULL[0m
Any thoughts about stripping colors during redirect? I do not want to use sed to find and replace as this looks tedious.
Thanks.
You can direct the output using the > character. printf "mytext" > out.txt will print "mytext" to the file "out.txt"
This is more directed to learning about BASH rather than creating a specific code.
---Problem: Write a Bash script that takes a list of login names on your computer system as command line arguments, and displays these login names, full names and user-ids of the users who own these logins (as contained in the /etc/passwd file), one per line. If a login name is invalid (not found in the /etc/passwd file), display the login name and an appropriate error message. ---
If I needed to create a code to fulfill this problem could I do it using a "choice" list like this:
read -p "Enter choice: " ch
if [ "$ch" = "1" ]; then
function_1
else
if [ "$ch" = "2" ]; then
function_2
else
if [ "$ch" = "3" ]; then
function_3
else
if [ "$ch" = "4" ]; then
function_4
else
if [ "$ch" = "5" ]; then
function_5
fi x5
or would it have to be completed using a grep and test method where by the user read input must be taken into variables Name1 Name2.... NameN and are tested to the ect/passwd file via grep command.
#!/bin/bash
# pgroup -- first version
# Fetch the GID from /etc/group
gid=$(grep "$̂1:" /etc/group | cut -d: -f3)
# Search users with that GID in /etc/passwd
grep "^[^:]*:[^:]*:[^:]*:$gid:" /etc/passwd | cut -d: -f1`enter code here`
Please explain the best you can with some generic code. I am still learning the basics and testing different ideas. I apologize if these are very vague concepts, I am still getting the hang of BASH.
You would:
Accept (read) from the user the username,
Check if the username exists by retrieving the record using grep,
If positive result (i.e. you got data), display it as needed,
Otherwise, display an error message (or whatever you need).
You are almost there (got how to get input, how to search using grep). What you need is to get the result of the grep into a variable that you can check. You may try something like:
Result=$(grep....)
and then check the contents of Result.
To me it looks like you're missing an important part of the problem: the names are passed as arguments to the script:
./script.sh name1 name2 name3
If this is the case, then a loop would be the most appropriate thing to use:
for login; do
printf '%s: %s\n' "$login" "$(grep "^$login" /etc/passwd)"
done
Note that a for loop iterates over the list of arguments passed to the script $# by default.
I'm trying to obtain the output of a bash command. More precisely, I need to store the number of lines that contains a string in a file:
variable_name = AAAAAAA
PATH_TO_SEARCH = .
COMMAND = "grep -R #{variable_name} #{PATH_TO_SEARCH} | wc -l"
To execute the command I tried both methods:
num_lines = %x[ #{COMMAND} ]
num_lines = `#{COMMAND}`
but the problem is: In "num_lines" I have 1) the number of lines that contain the string (OK!) and 2) output from grep like "grep: /home/file_example.txt: No such file or directory" (NO!).
I would like to store just the first output.
Looks like you may just need to suppress the error messages.
"You can use the -s or --no-messages flag to suppress errors." found from How can I have grep not print out 'No such file or directory' errors?
I want to pipe the output of a "template" file into MySQL, the file having variables like ${dbName} interspersed. What is the command line utility to replace these instances and dump the output to standard output?
The input file is considered to be safe, but faulty substitution definitions could exist. Performing the replacement should avoid performing unintended code execution.
Update
Here is a solution from yottatsa on a similar question that only does replacement for variables like $VAR or ${VAR}, and is a brief one-liner
i=32 word=foo envsubst < template.txt
Of course if i and word are in your environment, then it is just
envsubst < template.txt
On my Mac it looks like it was installed as part of gettext and from MacGPG2
Old Answer
Here is an improvement to the solution from mogsie on a similar question, my solution does not require you to escale double quotes, mogsie's does, but his is a one liner!
eval "cat <<EOF
$(<template.txt)
EOF
" 2> /dev/null
The power on these two solutions is that you only get a few types of shell expansions that don't occur normally $((...)), `...`, and $(...), though backslash is an escape character here, but you don't have to worry that the parsing has a bug, and it does multiple lines just fine.
Sed!
Given template.txt:
The number is ${i}
The word is ${word}
we just have to say:
sed -e "s/\${i}/1/" -e "s/\${word}/dog/" template.txt
Thanks to Jonathan Leffler for the tip to pass multiple -e arguments to the same sed invocation.
Use /bin/sh. Create a small shell script that sets the variables, and then parse the template using the shell itself. Like so (edit to handle newlines correctly):
File template.txt:
the number is ${i}
the word is ${word}
File script.sh:
#!/bin/sh
#Set variables
i=1
word="dog"
#Read in template one line at the time, and replace variables (more
#natural (and efficient) way, thanks to Jonathan Leffler).
while read line
do
eval echo "$line"
done < "./template.txt"
Output:
#sh script.sh
the number is 1
the word is dog
I was thinking about this again, given the recent interest, and I think that the tool that I was originally thinking of was m4, the macro processor for autotools. So instead of the variable I originally specified, you'd use:
$echo 'I am a DBNAME' | m4 -DDBNAME="database name"
Create rendertemplate.sh:
#!/usr/bin/env bash
eval "echo \"$(cat $1)\""
And template.tmpl:
Hello, ${WORLD}
Goodbye, ${CHEESE}
Render the template:
$ export WORLD=Foo
$ CHEESE=Bar ./rendertemplate.sh template.tmpl
Hello, Foo
Goodbye, Bar
template.txt
Variable 1 value: ${var1}
Variable 2 value: ${var2}
data.sh
#!/usr/bin/env bash
declare var1="value 1"
declare var2="value 2"
parser.sh
#!/usr/bin/env bash
# args
declare file_data=$1
declare file_input=$2
declare file_output=$3
source $file_data
eval "echo \"$(< $file_input)\"" > $file_output
./parser.sh data.sh template.txt parsed_file.txt
parsed_file.txt
Variable 1 value: value 1
Variable 2 value: value 2
Here's a robust Bash function that - despite using eval - should be safe to use.
All ${varName} variable references in the input text are expanded based on the calling shell's variables.
Nothing else is expanded: neither variable references whose names are not enclosed in {...} (such as $varName), nor command substitutions ($(...) and legacy syntax `...`), nor arithmetic substitutions ($((...)) and legacy syntax $[...]).
To treat a $ as a literal, \-escape it; e.g.:\${HOME}
Note that input is only accepted via stdin.
Example:
$ expandVarsStrict <<<'$HOME is "${HOME}"; `date` and \$(ls)' # only ${HOME} is expanded
$HOME is "/Users/jdoe"; `date` and $(ls)
Function source code:
expandVarsStrict(){
local line lineEscaped
while IFS= read -r line || [[ -n $line ]]; do # the `||` clause ensures that the last line is read even if it doesn't end with \n
# Escape ALL chars. that could trigger an expansion..
IFS= read -r -d '' lineEscaped < <(printf %s "$line" | tr '`([$' '\1\2\3\4')
# ... then selectively reenable ${ references
lineEscaped=${lineEscaped//$'\4'{/\${}
# Finally, escape embedded double quotes to preserve them.
lineEscaped=${lineEscaped//\"/\\\"}
eval "printf '%s\n' \"$lineEscaped\"" | tr '\1\2\3\4' '`([$'
done
}
The function assumes that no 0x1, 0x2, 0x3, and 0x4 control characters are present in the input, because those chars. are used internally - since the function processes text, that should be a safe assumption.
here's my solution with perl based on former answer, replaces environment variables:
perl -p -e 's/\$\{(\w+)\}/(exists $ENV{$1}?$ENV{$1}:"missing variable $1")/eg' < infile > outfile
I would suggest using something like Sigil:
https://github.com/gliderlabs/sigil
It is compiled to a single binary, so it's extremely easy to install on systems.
Then you can do a simple one-liner like the following:
cat my-file.conf.template | sigil -p $(env) > my-file.conf
This is much safer than eval and easier then using regex or sed
Here is a way to get the shell to do the substitution for you, as if the contents of the file were instead typed between double quotes.
Using the example of template.txt with contents:
The number is ${i}
The word is ${word}
The following line will cause the shell to interpolate the contents of template.txt and write the result to standard out.
i='1' word='dog' sh -c 'echo "'"$(cat template.txt)"'"'
Explanation:
i and word are passed as environment variables scopped to the execution of sh.
sh executes the contents of the string it is passed.
Strings written next to one another become one string, that string is:
'echo "' + "$(cat template.txt)" + '"'
Since the substitution is between ", "$(cat template.txt)" becomes the output of cat template.txt.
So the command executed by sh -c becomes:
echo "The number is ${i}\nThe word is ${word}",
where i and word are the specified environment variables.
If you are open to using Perl, that would be my suggestion. Although there are probably some sed and/or AWK experts that probably know how to do this much easier. If you have a more complex mapping with more than just dbName for your replacements you could extend this pretty easily, but you might just as well put it into a standard Perl script at that point.
perl -p -e 's/\$\{dbName\}/testdb/s' yourfile | mysql
A short Perl script to do something slightly more complicated (handle multiple keys):
#!/usr/bin/env perl
my %replace = ( 'dbName' => 'testdb', 'somethingElse' => 'fooBar' );
undef $/;
my $buf = <STDIN>;
$buf =~ s/\$\{$_\}/$replace{$_}/g for keys %replace;
print $buf;
If you name the above script as replace-script, it could then be used as follows:
replace-script < yourfile | mysql
file.tpl:
The following bash function should only replace ${var1} syntax and ignore
other shell special chars such as `backticks` or $var2 or "double quotes".
If I have missed anything - let me know.
script.sh:
template(){
# usage: template file.tpl
while read -r line ; do
line=${line//\"/\\\"}
line=${line//\`/\\\`}
line=${line//\$/\\\$}
line=${line//\\\${/\${}
eval "echo \"$line\"";
done < ${1}
}
var1="*replaced*"
var2="*not replaced*"
template file.tpl > result.txt
I found this thread while wondering the same thing. It inspired me to this (careful with the backticks)
$ echo $MYTEST
pass!
$ cat FILE
hello $MYTEST world
$ eval echo `cat FILE`
hello pass! world
Lots of choices here, but figured I'd toss mine on the heap. It is perl based, only targets variables of the form ${...}, takes the file to process as an argument and outputs the converted file on stdout:
use Env;
Env::import();
while(<>) { $_ =~ s/(\${\w+})/$1/eeg; $text .= $_; }
print "$text";
Of course I'm not really a perl person, so there could easily be a fatal flaw (works for me though).
It can be done in bash itself if you have control of the configuration file format. You just need to source (".") the configuration file rather than subshell it. That ensures the variables are created in the context of the current shell (and continue to exist) rather than the subshell (where the variable disappear when the subshell exits).
$ cat config.data
export parm_jdbc=jdbc:db2://box7.co.uk:5000/INSTA
export parm_user=pax
export parm_pwd=never_you_mind
$ cat go.bash
. config.data
echo "JDBC string is " $parm_jdbc
echo "Username is " $parm_user
echo "Password is " $parm_pwd
$ bash go.bash
JDBC string is jdbc:db2://box7.co.uk:5000/INSTA
Username is pax
Password is never_you_mind
If your config file cannot be a shell script, you can just 'compile' it before executing thus (the compilation depends on your input format).
$ cat config.data
parm_jdbc=jdbc:db2://box7.co.uk:5000/INSTA # JDBC URL
parm_user=pax # user name
parm_pwd=never_you_mind # password
$ cat go.bash
cat config.data
| sed 's/#.*$//'
| sed 's/[ \t]*$//'
| sed 's/^[ \t]*//'
| grep -v '^$'
| sed 's/^/export '
>config.data-compiled
. config.data-compiled
echo "JDBC string is " $parm_jdbc
echo "Username is " $parm_user
echo "Password is " $parm_pwd
$ bash go.bash
JDBC string is jdbc:db2://box7.co.uk:5000/INSTA
Username is pax
Password is never_you_mind
In your specific case, you could use something like:
$ cat config.data
export p_p1=val1
export p_p2=val2
$ cat go.bash
. ./config.data
echo "select * from dbtable where p1 = '$p_p1' and p2 like '$p_p2%' order by p1"
$ bash go.bash
select * from dbtable where p1 = 'val1' and p2 like 'val2%' order by p1
Then pipe the output of go.bash into MySQL and voila, hopefully you won't destroy your database :-).
In place perl editing of potentially multiple files, with backups.
perl -e 's/\$\{([^}]+)\}/defined $ENV{$1} ? $ENV{$1} : ""/eg' \
-i.orig \
-p config/test/*
I created a shell templating script named shtpl. My shtpl uses a jinja-like syntax which, now that I use ansible a lot, I'm pretty familiar with:
$ cat /tmp/test
{{ aux=4 }}
{{ myarray=( a b c d ) }}
{{ A_RANDOM=$RANDOM }}
$A_RANDOM
{% if $(( $A_RANDOM%2 )) == 0 %}
$A_RANDOM is even
{% else %}
$A_RANDOM is odd
{% endif %}
{% if $(( $A_RANDOM%2 )) == 0 %}
{% for n in 1 2 3 $aux %}
\$myarray[$((n-1))]: ${myarray[$((n-1))]}
/etc/passwd field #$n: $(grep $USER /etc/passwd | cut -d: -f$n)
{% endfor %}
{% else %}
{% for n in {1..4} %}
\$myarray[$((n-1))]: ${myarray[$((n-1))]}
/etc/group field #$n: $(grep ^$USER /etc/group | cut -d: -f$n)
{% endfor %}
{% endif %}
$ ./shtpl < /tmp/test
6535
6535 is odd
$myarray[0]: a
/etc/group field #1: myusername
$myarray[1]: b
/etc/group field #2: x
$myarray[2]: c
/etc/group field #3: 1001
$myarray[3]: d
/etc/group field #4:
More info on my github
To me this is the easiest and most powerful solution, you can even include other templates using the same command eval echo "$(<template.txt):
Example with nested template
create the template files, the variables are in regular bash syntax ${VARIABLE_NAME} or $VARIABLE_NAME
you have to escape special characters with \ in your templates otherwhise they will be interpreted by eval.
template.txt
Hello ${name}!
eval echo $(<nested-template.txt)
nested-template.txt
Nice to have you here ${name} :\)
create source file
template.source
declare name=royman
parse the template
source template.source && eval echo "$(<template.txt)"
the output
Hello royman!
Nice to have you here royman :)
envsubst
please don't use anything else (ie. don't eval)