Hi I'm using GNU awk version 3.1.5 and I've specified 2 variables in a KSH script
PKNAME= ls -lt /var/db/pkg | tr -s " " | cut -d" " -f9
PKDATE= ls -lt /var/db/pkg/$PKNAME/ | tr -s " " | cut -d" " -f6-8
I'm trying to prove that I'm getting the correct output, by running a test using
echo bar
awk -F, -v pkname="$PKNAME" -v pkdate="$PKDATE" 'BEGIN{print pkname, pkdate, "foo"; exit}'
echo baz
The output from this results in 2 blank spaces and foo, like so
bar
foo
baz
I have tried, double quoting the variables, single quotes and back ticks. Also tried double quotes with back ticks.
Any ideas why the variables are not being executed? I'm fairly new to awk and appreciate any help! Thanks
I suppose it is possible that it is not possible to run a sub shell comand within an awk statement. Is this true?
This has nothing to do with awk. The problem is in the way you're assigning your variables. Your lines should be like this:
PKNAME=$(ls -lt /var/db/pkg | tr -s " " | cut -d" " -f9)
There can be no spaces around either side of an assignment in the shell.
At the moment, you're running the command ls -lt ... with a variable PKNAME temporarily assigned to an empty string. In subsequent commands the variable remains unset.
Your awk command should remain unchanged, i.e. the shell variables should be passed like -v pkname="$PKNAME". As an aside, it's generally considered bad practice to use uppercase variable names, as these should be reserved for internal use by the shell.
Related
I run the command
df -gP /data1 /data2 | grep -v File | awk '{print $1}' |
awk -F/dev/ '$0=$2' | tr '\n' '
on the AIX shell (ksh) and it prints the output below:
lv_data01 lv_data02 root#testhost:/
However, I would like the output to be printed this way. Could someone help?
lv_data01 lv_data02
Using grep … | awk … | awk … is not necessary; a single awk could do the whole job. So could sed and it might even be easier. I'd be tempted to deal with the spacing by using:
x=$(df … | sed …); echo $x
The tr command, once corrected, replaces newlines with spaces, so the prompt follows without a newline before it. The ; echo suggestion adds the missing newline; the echo $x suggestion (note no double quotes) does too.
As for the sed command:
sed -n '/File/!{ s/[[:space:]].*//; s%^.*/dev/%%p; }'
Don't print anything by default
If the line doesn't match File (doing the work of grep -v):
remove the first space (blank or tab) and everything after it (doing the work of awk '{print $1}')
replace everything up to /dev/ with nothing and print (doing the work of awk -F/dev/ '{$0=$2}')
The command substitution and capture, followed by echo, deals with spaces and newlines.
So, my suggested solution is:
x=$(df -gP /data1 /data2 | sed -n '/File/!{ s/[[:space:]].*//; s%^.*/dev/%%p; }'); echo $x
You could add unset x after the echo if you are going to be using this directly in the shell and not in a shell script. If it'll be encapsulated in a shell script, you don't have to worry about it.
I'm blithely assuming the output from df -gP won't contain a path such as this, with two occurrences of /dev:
/who/knows/dev/lv_data01/dev/bin
If that's a real problem, you can fix the sed script, but I don't think it will be. It's one thing the second awk script in the question handles differently.
I have this script that's designed to assign variables to commands that collect information about a system and then echo them back. This works very well for the first few commands, but the last one continues to return the value without "PRETTY_NAME=" stripped out of the output.
Is there some problem with this that I'm not seeing?
I have tried using grep to separate awk:
grep PRETTY_NAME /etc/*-release | awk -F '=' '{print $2}'
Using escaped quotes:
awk -F \"=\" '/PRETTY_NAME/ {print $2}' /etc/*-release
Whole block (edited somewhat for relevance)
declare -A CMDS=(
[primaryMacAddress]="cat /sys/class/net/$(ip route show default | awk '/default/ {print $5}')/address"
[primaryIpAddress]="hostname --ip-address"
[hostname]="hostname"
[osType]="awk -F '=' '/PRETTY_NAME/ {print $2}' /etc/*-release"
)
#This bit is actually nested in another function
for kpair in "${!CMDS[#]}" do
echo "$kpair=\"$( eval ${CMDS[$kpair]} )\""
done
Results when run from .sh file:
osType="PRETTY_NAME="Red Hat Enterprise Linux Server 7.4 (Maipo)""
expected:
osType=""Red Hat Enterprise Linux Server 7.4 (Maipo)""
When this command is run by itself, it seems to work as intended:
$ awk -F '=' '/PRETTY_NAME/ {print $2}' /etc/*-release
"Red Hat Enterprise Linux Server 7.4 (Maipo)"
Because your Awk command is specified in double quotes, interior dollar signs are subject to special treatment: the $2 is treated as a parameter substitution by your shell, and so the array element doesn't store the text $2 but rather its expansion. The Awk interpreter never sees the $2 syntax.
However, you have a second problem in your command dispatcher. Your eval command does not prevent word splitting:
eval ${CMDS[$kpair]}
you want this:
eval "${CMDS[$kpair]}"
without the quotes, your command is arbitrarily chopped into fields on whitespace. Then eval catenates the pieces together, using one space between them, and evaluates the resulting syntax. The difference can be demonstrated with the following example:
$ cmd="awk '/foo/ { print \$1\" \"\$2 }'"
$ echo 'foo a' | eval $cmd
foo a
$ echo 'foo a' | eval "$cmd"
foo a
We can just use echo to understand the issue:
$ echo $cmd
awk '/foo/ { print $1" "$2 }'
$ echo "$cmd"
awk '/foo/ { print $1" "$2 }'
The substitution of $cmd and the subsequent word splitting is done irrespective of any shell syntax that `cmd contains. We can see the pieces like this:
$ for x in $cmd ; do echo "<$x>" ; done
<awk>
<'/foo/>
<{>
<print>
<$1">
<"$2>
<}'>
When we execute eval $cmd, the above pieces are generated and re-combined by eval and evaluated. Needless to say, you don't want your command syntax to be chopped up and re-combined like this; who knows what sort of hidden bug will arise. It may be okay for the commands you have now, but as a generic command dispatch mechanism, it is flawed.
Variable b has a string. Awk retrieves a substring which I want to assign to variable c. This is what I did:
#!/bin/bash
b=$(llsubmit multiple.cmd)
echo $b | c=$(awk '{
ret=match($0,".in.")
rwt=match($0,"\" has")
rqt=rwt-(ret+4)
subs=substr($0,(ret+4),rqt)
}')
... but I get a blank output for echo $c:
You can't pipe into an assignment.
c=$(echo "$b" | awk '{
ret=match($0,".in.")
rwt=match($0,"\" has")
rqt=rwt-(ret+4)
subs=substr($0,(ret+4),rqt)
}')
(Notice also the quoting around $b.)
But your Awk script looks rather complex. And it doesn't produce any output. Should it print something at the end? Without access to sample output from llsubmit this is mildly speculative, but I'm guessing something like this could work:
c=$(echo "b" | sed -n 's/.*\(\.in\.[^"]*\)" has .*/\1/p')
(Notice also the backslashes to make the dots match literally.)
You should properly then use double quotes in echo "$c" too (unless you are completely sure that the output cannot contain any shell metacharacters).
... And, of course, very often you don't want or need to store results in a variable in shell scripts if you can refactor your code into a pipeline. Perhaps you are really looking for something like
llsubmit multiple.cmd |
sed -n 's/.*\(\.in\.[^"]\)" has .*/p' |
while read -r job; do
: things with "$job"
done
It's hard to tell from your question since you didn't provide sample input and expected output but is this what you're trying to do:
$ b='foo .in.bar has'
$ c="${b% has*}"
$ c="${c#*.in.}"
$ echo "$c"
bar
i would like to create a bash script that creates the md5-hash of a string.
BUT the string can contain special characters and spaces. How can i get it that such a string is readable for eg. md5sum?
I have written the following script as "md5.sh":
#!/bin/bash
echo -n $1 | md5sum | awk '{print $1}'
But if i use "./md5.sh " (with a space at the end) this will not be recognized.
Also quoted cannot be read from the script. And a single " will end in an prompt...
Hope someone can help me :)
First, you need to quote the parameter in the script (and use printf; the world would be a better place if people forgot echo existed):
printf '%s' "$1" | md5sum | awk '{print $1}'
Second, to pass an actual space as the argument, it must be quoted as well so that the shell doesn't discard it:
./md5.sh " "
I am trying to do the following.
foo="foo:foo1"
cc= `$foo | cut -f2 -d:`
I understand why this would not work but I am at a loss as to do this.
Thanks in advance.
Try this:
foo="foo:foo1"
cc=`echo $foo | cut -f2 -d:`
There are 2 changes to make:
You need to echo the value of shell
variable foo and then cut it.
You must not have white spaces around =
when assigning a value to a shell
variable.
in bourne, you can use set. No external command needed.
$ foo="foo:foo1"
$ IFS=":"
$ set -- $foo
$ echo $2
foo1