I have two shell script files test1.sh and test2.sh . I have another file called translogs.txt.
Now I need to copy the values of two variables in test1.sh to translog.txt and the same variables need to be copied to the corresponding values in test2.sh.
test1.sh
#!/bin/sh
ONE="000012"
TIME="2013-02-19 15:31:06"
echo -e "$ONE\n$TIME">translog.txt;
translog.txt
ONE="000012"
TIME="2013-02-19 15:31:06"
But here in test2.sh, I want the same value as in translog.txt to the corresponding variable
test2.sh
#!/bin/sh
ONE="000012"
TIME="2013-02-19 15:31:06"
1 Diry solution
$> cat translog.txt
ONE="000012"
TIME="2013-02-19 15:31:06"
With perl regular expression grep could match these value using lookbehind operator.
$> grep --only-matching --perl-regex "(?<=ONE\=).*" translog.txt
"000012"
And for TIME:
$> grep --only-matching --perl-regex "(?<=TIME\=).*" translog.txt
"2013-02-19 15:31:06"
So from withing the test2.sh script you can use it like this:
#!/bin/bash
ONE=`grep --only-matching --perl-regex "(?<=ONE\=).*" translog.txt`
TIME=`grep --only-matching --perl-regex "(?<=TIME\=).*" translog.txt`
2 Command line solution
Another solution pointed out in one of the links below would be to use:
the source (a.k.a. .) command to load all of the variables in the file into the current shell:
$ source translog.txt
Now you have access to the values of the variables defined inside the file:
$ echo $TIME
"2013-02-19 15:31:06"
3 Easiest solution
Another approach was mentioned by #user2086768. Put these lines to `test2.sh:
#!/bin/bash
eval $(cat translog.txt)
And as a result you would have assigned the two variables within the test2.sh script:
ONE="000012"
TIME="2013-02-19 15:31:06"
you can easily check that adding:
echo $ONE
echo $TIME
Check also these links:
how to get value of variable config in bash?
Here's a more general overview: Loading data into bash variables
As translog.txt is valid bash code, you could do:
source translog.txt
in test2.sh, ONE and TWO would be available in test2.sh.
A word of warning, that does open you up to shell script injection attacks if the values for ONE and TWO were to come from an untrusted source.
If your translog.txt is as you say, then this will work
#!/bin/sh
while read aa
do
eval "$aa"
done < translog.txt
eval should work for you.
Try to use this version of test2.sh:
test2.sh
#!/bin/bash
eval $(cat translog.txt)
echo $ONE
echo $TIME
This outputs:
000012
2013-02-19 15:31:06
Related
I have two shell scripts that I'd like to invoke from a C program. I would like shell variables set in the first script to be visible in the second. Here's what it would look like:
a.sh:
var=blah
<save vars>
b.sh:
<restore vars>
echo $var
The best I've come up with so far is a variant on "set > /tmp/vars" to save the variables and "eval $(cat /tmp/vars)" to restore them. The "eval" chokes when it tries to restore a read-only variable, so I need to grep those out. A list of these variables is available via "declare -r". But there are some vars which don't show up in this list, yet still can't be set in eval, e.g. BASH_ARGC. So I need to grep those out, too.
At this point, my solution feels very brittle and error-prone, and I'm not sure how portable it is. Is there a better way to do this?
One way to avoid setting problematic variables is by storing only those which have changed during the execution of each script. For example,
a.sh:
set > /tmp/pre
foo=bar
set > /tmp/post
grep -v -F -f/tmp/pre /tmp/post > /tmp/vars
b.sh:
eval $(cat /tmp/vars)
echo $foo
/tmp/vars contains this:
PIPESTATUS=([0]="0")
_=
foo=bar
Evidently evaling the first two lines has no adverse effect.
If you can use a common prefix on your variable names, here is one way to do it:
# save the variables
yourprefix_width=1200
yourprefix_height=2150
yourprefix_length=1975
yourprefix_material=gravel
yourprefix_customer_array=("Acme Plumbing" "123 Main" "Anytown")
declare -p $(echo ${!yourprefix#}) > varfile
# load the variables
while read -r line
do
if [[ $line == declare\ * ]]
then
eval "$line"
fi
done < varfile
Of course, your prefix will be shorter. You could do further validation upon loading the variables to make sure that the variable names conform to your naming scheme.
The advantage of using declare is that it is more secure than just using eval by itself.
If you need to, you can filter out variables that are marked as readonly or select variables that are marked for export.
Other commands of interest (some may vary by Bash version):
export - without arguments, lists all exported variables using a declare format
declare -px - same as the previous command
declare -pr - lists readonly variables
If it's possible for a.sh to call b.sh, it will carry over if they're exported. Or having a parent set all the values necessary and then call both. That's the most secure and sure method I can think of.
Not sure if it's accepted dogma, but:
bash -c 'export foo=bar; env > xxxx'
env `cat xxxx` otherscript.sh
The otherscript will have the env printed to xxxx ...
Update:
Also note:
man execle
On how to set environment variables for another system call from within C, if you need to do that. And:
man getenv
and http://www.crasseux.com/books/ctutorial/Environment-variables.html
An alternative to saving and restoring shell state would be to make the C program and the shell program work in parallel: the C program starts the shell program, which runs a.sh, then notifies the C program (perhaps passing some information it's learned from executing a.sh), and when the C program is ready for more it tells the shell program to run b.sh. The shell program would look like this:
. a.sh
echo "information gleaned from a"
arguments_for_b=$(read -r)
. b.sh
And the general structure of the C program would be:
set up two pairs of pipes, one for C->shell and one for shell->C
fork, exec the shell wrapper
read information gleaned from a on the shell->C pipe
more processing
write arguments for b on the C->shell pipe
wait for child process to end
I went looking for something similar and couldn't find it either, so I made the two scripts below. To start, just say shellstate, then probably at least set -i and set -o emacs which this reset_shellstate doesn't do for you. I don't know a way to ask bash which variables it thinks are special.
~/bin/reset_shellstate:
#!/bin/bash
__="$PWD/shellstate_${1#_}"
trap '
declare -p >"'"$__"'"
trap >>"'"$__"'"
echo cd \""$PWD"\" >>"'"$__"'" # setting PWD did this already, but...
echo set +abefhikmnptuvxBCEHPT >>"'"$__"'"
echo set -$- >>"'"$__"'" # must be last before sed, see $s/s//2 below
sed -ri '\''
$s/s//2
s,^trap --,trap,
/^declare -[^ ]*r/d
/^declare -[^ ]* [A-Za-z0-9_]*[^A-Za-z0-9_=]/d
/^declare -[^ ]* [^= ]*_SESSION_/d
/^declare -[^ ]* BASH[=_]/d
/^declare -[^ ]* (DISPLAY|GROUPS|SHLVL|XAUTHORITY)=/d
/^declare -[^ ]* WINDOW(ID|PATH)=/d
'\'' "'"$__"'"
shopt -op >>"'"$__"'"
shopt -p >>"'"$__"'"
declare -f >>"'"$__"'"
echo "Shell state saved in '"$__"'"
' 0
unset __
~/bin/shellstate:
#!/bin/bash
shellstate=shellstate_${1#_}
test -s $shellstate || reset_shellstate $1
shift
bash --noprofile --init-file shellstate_${1#_} -is "$#"
exit $?
See also my previous question.
So... I have a script:
function go_loop (){
for i in `grep -v ^# $1`; do
$2
done
}
go_loop "/tmp/text.txt" "echo $i"
I should have in a result:
9
20
21
...
But apparently I only get an empty result. How can I feed the second input parameter to the loop?
Please don't advice me do this:
for i in `grep -v ^# $1`; do
echo $i
done
I need to make 2 input parameters, first - name of file, second - name of execution command
You need to eval the second parameter like this:
eval $2
and pass it like this:
go_loop "/tmp/text.txt" 'echo $i'
You can do this using exec inside your loop, which will run the $2 as bash command:
[root#box ~]# ./test.sh 1 ls
test.sh tests_passed.txt
[root#box ~]# cat test
exec $2
The exec builtin command is used to
replace the shell with a given program (executing it, not as new process)
set redirections for the program to execute or for the current shell
how can i make a bash script to tell the script this:
i will tell the bash like:
#!/bin/bash
include /usr/local/serverinfo.txt or.sh
rsync -avz $location root#$host:/$location2
all of this $location, $host , $location2, to be entered in /usr/local/serverinfo.txt
how can i tell the bash script to get this infos from the file,
if i put them in the same file will work just perfect, however i whant it to be outside of the file, any ideea?
let me know, thanks.
You can use source, or equivalently ., which takes another file as an argument and executes it. This assumes that the file you are sourceing contains valid bash syntax.
script.sh:
#!/bin/bash
var=1
source inc.sh # or . inc.sh
echo $var
inc.sh
var=2
output:
2
This depends on how the data in serverinfo.txt is formatted.
If it is a simple list like
/this/is/the/first/location
/this/is/the/host
/this/is/the/second/location
then you can do
location=$(sed -n '1p' /path/to/serverinfo.txt)
host=$(sed -n '2p' /path/to/serverinfo.txt)
location2=$(sed -n '3p' /path/to/serverinfo.txt)
Consider a ASCII text file (lets say it contains code of a non-shell scripting language):
Text_File.msh:
spool on to '$LOG_FILE_PATH/logfile.log';
login 'username' 'password';
....
Now if this were a shell script I could run it as $ sh Text_File.msh and the shell would automatically expand the variables.
What I want to do is have shell expand these variables and then create a new file as Text_File_expanded.msh as follows:
Text_File_expanded.msh:
spool on to '/expanded/path/of/the/log/file/../logfile.log';
login 'username' 'password';
....
Consider:
$ a=123
$ echo "$a"
123
So technically this should do the trick:
$ echo "`cat Text_File.msh`" > Text_File_expanded.msh
...but it doesn't work as expected and the output-file while is identical to the source.
So I am unsure how to achieve this.. My goal is make it easier to maintain the directory paths embedded within my non-shell scripts. These scripts cannot contain any UNIX code as it is not compiled by the UNIX shell.
This question has been asked in another thread, and this is the best answer IMO:
export LOG_FILE_PATH=/expanded/path/of/the/log/file/../logfile.log
cat Text_File.msh | envsubst > Text_File_expanded.msh
if on Mac, install gettext first: brew install gettext
see:
Forcing bash to expand variables in a string loaded from a file
This solution is not elegant, but it works. Create a script call shell_expansion.sh:
echo 'cat <<END_OF_TEXT' > temp.sh
cat "$1" >> temp.sh
echo 'END_OF_TEXT' >> temp.sh
bash temp.sh >> "$2"
rm temp.sh
You can then invoke this script as followed:
bash shell_expansion.sh Text_File.msh Text_File_expanded.msh
If you want it in one line (I'm not a bash expert so there may be caveats to this but it works everywhere I've tried it):
when test.txt contains
${line1}
${line2}
then:
>line1=fark
>line2=fork
>value=$(eval "echo \"$(cat test.txt)\"")
>echo "$value"
line1 says fark
line2 says fork
Obviously if you just want to print it you can take out the extra value=$() and echo "$value".
If a Perl solution is ok for you:
Sample file:
$ cat file.sh
spool on to '$HOME/logfile.log';
login 'username' 'password';
Solution:
$ perl -pe 's/\$(\w+)/$ENV{$1}/g' file.sh
spool on to '/home/user/logfile.log';
login 'username' 'password';
One limitation of the above answers is that they both require the variables to be exported to the environment. Here's what i came up with that would allow the variables to be local to the current shell script:
#!/bin/sh
FOO=bar;
FILE=`mktemp`; # Let the shell create a temporary file
trap 'rm -f $FILE' 0 1 2 3 15; # Clean up the temporary file
(
echo 'cat <<END_OF_TEXT'
cat "$#"
echo 'END_OF_TEXT'
) > $FILE
. $FILE
The above example allows the variable $FOO to be substituted in the files named on the command line. I'm sure it can be improved, but this works for me so far.
Thanks to both previous answers for their ideas!
If the variables you want to translate are known and limited in number, you can always do the translation yourself:
sed "s/\$LOG_FILE_PATH/$LOG_FILE_PATH/g" input > output
And also assuming the variable itself is already known
This solution allows you to keep the same formatting in the ouput file
Copy and paste the following lines in your script
cat $1 | while read line
do
eval $line
echo $line
eval echo $line
done | uniq | grep -v '\$'
this will read the file passed as argument line by line, and then process to try and print each line twice:
- once without substitution
- once with substitution of the variables.
then remove the duplicate lines
then remove the lines containing visible variables ($)
Yes eval should be used carefully, but it provided me this simple oneliner for my problem. Below is an example using your filename:
eval "echo \"$(<Text_File.msh)\""
I use printf instead of echo for my own purposes, but that should do the trick. Thank you abyss.7 providing the link that solve my problem. Hope it helps.
Create an ascii file test.txt with the following content:
Try to replace this ${myTestVariable1}
bla bla
....
Now create a file “sub.sed” containing variable names, eg
's,${myTestVariable1},'"${myTestVariable1}"',g;
s,${myTestVariable2},'"${myTestVariable2}"',g;
s,${myTestVariable3},'"${myTestVariable3}"',g;
s,${myTestVariable4},'"${myTestVariable4}"',g'
Open a terminal move to the folder containing test.txt and sub.sed.
Define the value of the varible to be replaced
myTestVariable1=SomeNewText
Now call sed to replace that variable
sed "$(eval echo $(cat sub.sed))" test.txt > test2.txt
The output will be
$cat test2.txt
Try to replace this SomeNewText
bla bla
....
#logfiles.list:
$EAMSROOT/var/log/LinuxOSAgent.log
$EAMSROOT/var/log/PanacesServer.log
$EAMSROOT/var/log/PanacesStrutsGUI.log
#My Program:
cat logfiles.list | while read line
do
eval Eline=$line
echo $Eline
done
cat file
$VAR
cat script
#!/bin/bash
CONTENT=$(<file)
echo $CONTENT
./script
$VAR
I'd like to get the variable's actual value, not "$VAR". How to get a weaker quoting? Many thanks!
This should do it:
CONTENT=$(eval echo -e `<file`)