Mixing
awk regex word boundary
I have two Linux machines. One is 4.4.12-99, one is 4.4.143. I just ran apt upgrade on them both.
I have an awk statement that contains a regex that works on 4.4.143, but fails on 4.4.12-99. I have searched for days and tried multiple different syntaxes to discover what can be wrong. awk is not failing or complaining, it's just not matching the word boundary. The scripts are the same on each machine and work fine except for this awk statement. On the one that is not working properly, I can cause it to match everything and provide that result.
ip=$(awk -v sUSER="$sUSER" 'BEGIN{gsub(/./,"\.",sUSER)}match($0,/[0-9]+.[0-9]+.[0-9]+.[0-9]+/) && $0 ~ ("[^[:alnum:]]"sUSER"$") && $0 !~ /^$/ && $0 !~ /^#/{print $1}' /etc/hosts )
awk looks into the /etc/hosts file with a variable, $sUSER and tried to match a user to an associated IP address.
I cant figure out what I am doing wrong.
regex bash awk match
asked Nov 21 '18 at 17:22
WesZWesZ
527
|
show 4 more comments
I have two Linux machines. One is 4.4.12-99, one is 4.4.143. I just ran apt upgrade on them both.
I have an awk statement that contains a regex that works on 4.4.143, but fails on 4.4.12-99. I have searched for days and tried multiple different syntaxes to discover what can be wrong. awk is not failing or complaining, it's just not matching the word boundary. The scripts are the same on each machine and work fine except for this awk statement. On the one that is not working properly, I can cause it to match everything and provide that result.
ip=$(awk -v sUSER="$sUSER" 'BEGIN{gsub(/./,"\.",sUSER)}match($0,/[0-9]+.[0-9]+.[0-9]+.[0-9]+/) && $0 ~ ("[^[:alnum:]]"sUSER"$") && $0 !~ /^$/ && $0 !~ /^#/{print $1}' /etc/hosts )
awk looks into the /etc/hosts file with a variable, $sUSER and tried to match a user to an associated IP address.
I cant figure out what I am doing wrong.
regex bash awk match
asked Nov 21 '18 at 17:22
WesZWesZ
527
What is the sample file you are running this on? Give us a proper reproducible example to help us solve your problem
– Inian
Nov 21 '18 at 17:26
Hello, the sample file is the /etc/hosts file as shown at the end of the awk statement and once again, as is stated, this awk looks into the /etc/hosts file and extracts an IP address for a given username/hostname.
– WesZ
Nov 21 '18 at 17:57
1
@WesZ, your previous thread stackoverflow.com/questions/53353494/… how different it is please do let us know? That thread also you have not informed anyone about what happened, so please don't do so, take questions/problems one by one only
– RavinderSingh13
Nov 21 '18 at 18:01
It says:Thanks. Hello. I wanted to post my final line of code that provides the correct output. I appreciate all of the help and guidance from those who responded. I wanted to post the final code in case someone in the future can find it useful.
– WesZ
Nov 21 '18 at 18:06
@WesZ, could you please do let us know if you have taken guidance from my or hek2mgl post. Both are based on different approaches but you should try it out both and let individual know about its status then/.
– RavinderSingh13
Nov 21 '18 at 18:08
|
show 4 more comments
I have two Linux machines. One is 4.4.12-99, one is 4.4.143. I just ran apt upgrade on them both.
I have an awk statement that contains a regex that works on 4.4.143, but fails on 4.4.12-99. I have searched for days and tried multiple different syntaxes to discover what can be wrong. awk is not failing or complaining, it's just not matching the word boundary. The scripts are the same on each machine and work fine except for this awk statement. On the one that is not working properly, I can cause it to match everything and provide that result.
ip=$(awk -v sUSER="$sUSER" 'BEGIN{gsub(/./,"\.",sUSER)}match($0,/[0-9]+.[0-9]+.[0-9]+.[0-9]+/) && $0 ~ ("[^[:alnum:]]"sUSER"$") && $0 !~ /^$/ && $0 !~ /^#/{print $1}' /etc/hosts )
awk looks into the /etc/hosts file with a variable, $sUSER and tried to match a user to an associated IP address.
I cant figure out what I am doing wrong.
regex bash awk match
asked Nov 21 '18 at 17:22
WesZWesZ
527
I have two Linux machines. One is 4.4.12-99, one is 4.4.143. I just ran apt upgrade on them both.
I have an awk statement that contains a regex that works on 4.4.143, but fails on 4.4.12-99. I have searched for days and tried multiple different syntaxes to discover what can be wrong. awk is not failing or complaining, it's just not matching the word boundary. The scripts are the same on each machine and work fine except for this awk statement. On the one that is not working properly, I can cause it to match everything and provide that result.
ip=$(awk -v sUSER="$sUSER" 'BEGIN{gsub(/./,"\.",sUSER)}match($0,/[0-9]+.[0-9]+.[0-9]+.[0-9]+/) && $0 ~ ("[^[:alnum:]]"sUSER"$") && $0 !~ /^$/ && $0 !~ /^#/{print $1}' /etc/hosts )
awk looks into the /etc/hosts file with a variable, $sUSER and tried to match a user to an associated IP address.
I cant figure out what I am doing wrong.
regex bash awk match
regex bash awk match
asked Nov 21 '18 at 17:22
WesZWesZ
527
asked Nov 21 '18 at 17:22
WesZWesZ
527
asked Nov 21 '18 at 17:22
WesZWesZ
527
asked Nov 21 '18 at 17:22
WesZWesZ
527
asked Nov 21 '18 at 17:22
WesZWesZ
527
527
What is the sample file you are running this on? Give us a proper reproducible example to help us solve your problem
– Inian
Nov 21 '18 at 17:26
Hello, the sample file is the /etc/hosts file as shown at the end of the awk statement and once again, as is stated, this awk looks into the /etc/hosts file and extracts an IP address for a given username/hostname.
– WesZ
Nov 21 '18 at 17:57
1
@WesZ, your previous thread stackoverflow.com/questions/53353494/… how different it is please do let us know? That thread also you have not informed anyone about what happened, so please don't do so, take questions/problems one by one only
– RavinderSingh13
Nov 21 '18 at 18:01
It says:Thanks. Hello. I wanted to post my final line of code that provides the correct output. I appreciate all of the help and guidance from those who responded. I wanted to post the final code in case someone in the future can find it useful.
– WesZ
Nov 21 '18 at 18:06
@WesZ, could you please do let us know if you have taken guidance from my or hek2mgl post. Both are based on different approaches but you should try it out both and let individual know about its status then/.
– RavinderSingh13
Nov 21 '18 at 18:08
|
show 4 more comments
What is the sample file you are running this on? Give us a proper reproducible example to help us solve your problem
– Inian
Nov 21 '18 at 17:26
Hello, the sample file is the /etc/hosts file as shown at the end of the awk statement and once again, as is stated, this awk looks into the /etc/hosts file and extracts an IP address for a given username/hostname.
– WesZ
Nov 21 '18 at 17:57
1
@WesZ, your previous thread stackoverflow.com/questions/53353494/… how different it is please do let us know? That thread also you have not informed anyone about what happened, so please don't do so, take questions/problems one by one only
– RavinderSingh13
Nov 21 '18 at 18:01
It says:Thanks. Hello. I wanted to post my final line of code that provides the correct output. I appreciate all of the help and guidance from those who responded. I wanted to post the final code in case someone in the future can find it useful.
– WesZ
Nov 21 '18 at 18:06
@WesZ, could you please do let us know if you have taken guidance from my or hek2mgl post. Both are based on different approaches but you should try it out both and let individual know about its status then/.
– RavinderSingh13
Nov 21 '18 at 18:08
What is the sample file you are running this on? Give us a proper reproducible example to help us solve your problem
– Inian
Nov 21 '18 at 17:26
What is the sample file you are running this on? Give us a proper reproducible example to help us solve your problem
– Inian
Nov 21 '18 at 17:26
Hello, the sample file is the /etc/hosts file as shown at the end of the awk statement and once again, as is stated, this awk looks into the /etc/hosts file and extracts an IP address for a given username/hostname.
– WesZ
Nov 21 '18 at 17:57
Hello, the sample file is the /etc/hosts file as shown at the end of the awk statement and once again, as is stated, this awk looks into the /etc/hosts file and extracts an IP address for a given username/hostname.
– WesZ
Nov 21 '18 at 17:57
1
1
@WesZ, your previous thread stackoverflow.com/questions/53353494/… how different it is please do let us know? That thread also you have not informed anyone about what happened, so please don't do so, take questions/problems one by one only
– RavinderSingh13
Nov 21 '18 at 18:01
@WesZ, your previous thread stackoverflow.com/questions/53353494/… how different it is please do let us know? That thread also you have not informed anyone about what happened, so please don't do so, take questions/problems one by one only
– RavinderSingh13
Nov 21 '18 at 18:01
It says:Thanks. Hello. I wanted to post my final line of code that provides the correct output. I appreciate all of the help and guidance from those who responded. I wanted to post the final code in case someone in the future can find it useful.
– WesZ
Nov 21 '18 at 18:06
It says:Thanks. Hello. I wanted to post my final line of code that provides the correct output. I appreciate all of the help and guidance from those who responded. I wanted to post the final code in case someone in the future can find it useful.
– WesZ
Nov 21 '18 at 18:06
@WesZ, could you please do let us know if you have taken guidance from my or hek2mgl post. Both are based on different approaches but you should try it out both and let individual know about its status then/.
– RavinderSingh13
Nov 21 '18 at 18:08
@WesZ, could you please do let us know if you have taken guidance from my or hek2mgl post. Both are based on different approaches but you should try it out both and let individual know about its status then/.
– RavinderSingh13
Nov 21 '18 at 18:08
|
show 4 more comments
2 Answers
2
active
oldest
votes
hek2mgl's answer is what you should use.
For your awk question, GNU awk regular expressions are documented here: https://www.gnu.org/software/gnulib/manual/html_node/gnu_002dawk-regular-expression-syntax.html
They use < and > as zero-width word boundary markers, so you can do
gawk -v sUSER="$sUSER" '
BEGIN {
gsub(/./,"\.",sUSER)
ipv4Re = "^[0-9]+(\.[0-9]+){3}$"
sUserRe = "\<" sUSER "\>"
}
/^$/ || /^#/ {next}
$1 ~ ipv4Re && $0 ~ sUserRe {print $1}
' /etc/hosts
(whitespace is nice, you should try using it)
another approach is looping over the fields and using string equality which automatically encompasses word boundaries. This will work with gawk or mawk
awk -v sUSER="$sUSER" '
!/^#/ {for (i=2; i<=NF; i++) if ($i == sUSER) print $1}
' /etc/hosts
answered Nov 21 '18 at 20:05
glenn jackmanglenn jackman
167k26147238
Whitespace is your friend. Indentation solves a lot of debugging, lol
– Paul Hodges
Nov 21 '18 at 20:54
Hi Glenn - I used this code and my symptoms are the same. I have actually tried using this "awk" statement on 5 different machines, 4 of them it did not work and one it did work. It worked on the one that it always worked on. Do you think maybe there is a missing library or something? Maybe I should try and reinstall awk/mawk/gawk ?? I am really becoming perplexed with this. I have checked syslog and it reports nothing.
– WesZ
Nov 22 '18 at 9:47
I did note that the word boundaries are a GNU awk feature. GNU awk is not installed by default on some distributions: what awk are you running? And awk errors will not be syslogged.
– glenn jackman
Nov 22 '18 at 14:06
Well... it seems "Houston.....we have a problem...." The one that works fine is GNU Awk 4.1.3, API: 1.1 (GNU MPFR 3.1.4, GNU MP 6.1.0) and the one that has problems is awk: not an option: --version awk -Wversion 2>/dev/null || awk --version mawk 1.3.3 Nov 1996, Copyright (C) Michael D. Brennan so what should I do?
– WesZ
Nov 22 '18 at 16:11
So is it gawk that needs to be installed to get the GNU stuff?
– WesZ
Nov 22 '18 at 16:18
|
show 2 more comments
What you basically want to do is a local hostname lookup. There is a tool called getent for that purpose:
getent -s files hosts "${sUSER}" | cut -d' ' -f1
-s files tells getent to only use the local host databases (not DNS) which is /etc/hosts.
answered Nov 21 '18 at 17:53
hek2mglhek2mgl
108k13144166
Hello, this getent works, but can it be made to use a specified file? I looked on the man page, but it wasn't mentioned. I can use this, I would need to re-write some code to append the /etc/hosts file. If I can, I would like to use the awk code, although it is becoming a bit clunky... so maybe this is a better solution. Thanks.
– WesZ
Nov 21 '18 at 19:03
getent hostsis always using/etc/hosts. What you basically want to do is a local hostname lookup.getent -s filesis made for that.
– hek2mgl
Nov 21 '18 at 19:13
add a comment |
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2 Answers
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2 Answers
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hek2mgl's answer is what you should use.
For your awk question, GNU awk regular expressions are documented here: https://www.gnu.org/software/gnulib/manual/html_node/gnu_002dawk-regular-expression-syntax.html
They use < and > as zero-width word boundary markers, so you can do
gawk -v sUSER="$sUSER" '
BEGIN {
gsub(/./,"\.",sUSER)
ipv4Re = "^[0-9]+(\.[0-9]+){3}$"
sUserRe = "\<" sUSER "\>"
}
/^$/ || /^#/ {next}
$1 ~ ipv4Re && $0 ~ sUserRe {print $1}
' /etc/hosts
(whitespace is nice, you should try using it)
another approach is looping over the fields and using string equality which automatically encompasses word boundaries. This will work with gawk or mawk
awk -v sUSER="$sUSER" '
!/^#/ {for (i=2; i<=NF; i++) if ($i == sUSER) print $1}
' /etc/hosts
answered Nov 21 '18 at 20:05
glenn jackmanglenn jackman
167k26147238
Whitespace is your friend. Indentation solves a lot of debugging, lol
– Paul Hodges
Nov 21 '18 at 20:54
Hi Glenn - I used this code and my symptoms are the same. I have actually tried using this "awk" statement on 5 different machines, 4 of them it did not work and one it did work. It worked on the one that it always worked on. Do you think maybe there is a missing library or something? Maybe I should try and reinstall awk/mawk/gawk ?? I am really becoming perplexed with this. I have checked syslog and it reports nothing.
– WesZ
Nov 22 '18 at 9:47
I did note that the word boundaries are a GNU awk feature. GNU awk is not installed by default on some distributions: what awk are you running? And awk errors will not be syslogged.
– glenn jackman
Nov 22 '18 at 14:06
Well... it seems "Houston.....we have a problem...." The one that works fine is GNU Awk 4.1.3, API: 1.1 (GNU MPFR 3.1.4, GNU MP 6.1.0) and the one that has problems is awk: not an option: --version awk -Wversion 2>/dev/null || awk --version mawk 1.3.3 Nov 1996, Copyright (C) Michael D. Brennan so what should I do?
– WesZ
Nov 22 '18 at 16:11
So is it gawk that needs to be installed to get the GNU stuff?
– WesZ
Nov 22 '18 at 16:18
|
show 2 more comments
hek2mgl's answer is what you should use.
For your awk question, GNU awk regular expressions are documented here: https://www.gnu.org/software/gnulib/manual/html_node/gnu_002dawk-regular-expression-syntax.html
They use < and > as zero-width word boundary markers, so you can do
gawk -v sUSER="$sUSER" '
BEGIN {
gsub(/./,"\.",sUSER)
ipv4Re = "^[0-9]+(\.[0-9]+){3}$"
sUserRe = "\<" sUSER "\>"
}
/^$/ || /^#/ {next}
$1 ~ ipv4Re && $0 ~ sUserRe {print $1}
' /etc/hosts
(whitespace is nice, you should try using it)
another approach is looping over the fields and using string equality which automatically encompasses word boundaries. This will work with gawk or mawk
awk -v sUSER="$sUSER" '
!/^#/ {for (i=2; i<=NF; i++) if ($i == sUSER) print $1}
' /etc/hosts
answered Nov 21 '18 at 20:05
glenn jackmanglenn jackman
167k26147238
Whitespace is your friend. Indentation solves a lot of debugging, lol
– Paul Hodges
Nov 21 '18 at 20:54
Hi Glenn - I used this code and my symptoms are the same. I have actually tried using this "awk" statement on 5 different machines, 4 of them it did not work and one it did work. It worked on the one that it always worked on. Do you think maybe there is a missing library or something? Maybe I should try and reinstall awk/mawk/gawk ?? I am really becoming perplexed with this. I have checked syslog and it reports nothing.
– WesZ
Nov 22 '18 at 9:47
I did note that the word boundaries are a GNU awk feature. GNU awk is not installed by default on some distributions: what awk are you running? And awk errors will not be syslogged.
– glenn jackman
Nov 22 '18 at 14:06
Well... it seems "Houston.....we have a problem...." The one that works fine is GNU Awk 4.1.3, API: 1.1 (GNU MPFR 3.1.4, GNU MP 6.1.0) and the one that has problems is awk: not an option: --version awk -Wversion 2>/dev/null || awk --version mawk 1.3.3 Nov 1996, Copyright (C) Michael D. Brennan so what should I do?
– WesZ
Nov 22 '18 at 16:11
So is it gawk that needs to be installed to get the GNU stuff?
– WesZ
Nov 22 '18 at 16:18
|
show 2 more comments
hek2mgl's answer is what you should use.
For your awk question, GNU awk regular expressions are documented here: https://www.gnu.org/software/gnulib/manual/html_node/gnu_002dawk-regular-expression-syntax.html
They use < and > as zero-width word boundary markers, so you can do
gawk -v sUSER="$sUSER" '
BEGIN {
gsub(/./,"\.",sUSER)
ipv4Re = "^[0-9]+(\.[0-9]+){3}$"
sUserRe = "\<" sUSER "\>"
}
/^$/ || /^#/ {next}
$1 ~ ipv4Re && $0 ~ sUserRe {print $1}
' /etc/hosts
(whitespace is nice, you should try using it)
another approach is looping over the fields and using string equality which automatically encompasses word boundaries. This will work with gawk or mawk
awk -v sUSER="$sUSER" '
!/^#/ {for (i=2; i<=NF; i++) if ($i == sUSER) print $1}
' /etc/hosts
answered Nov 21 '18 at 20:05
glenn jackmanglenn jackman
167k26147238
hek2mgl's answer is what you should use.
For your awk question, GNU awk regular expressions are documented here: https://www.gnu.org/software/gnulib/manual/html_node/gnu_002dawk-regular-expression-syntax.html
They use < and > as zero-width word boundary markers, so you can do
gawk -v sUSER="$sUSER" '
BEGIN {
gsub(/./,"\.",sUSER)
ipv4Re = "^[0-9]+(\.[0-9]+){3}$"
sUserRe = "\<" sUSER "\>"
}
/^$/ || /^#/ {next}
$1 ~ ipv4Re && $0 ~ sUserRe {print $1}
' /etc/hosts
(whitespace is nice, you should try using it)
another approach is looping over the fields and using string equality which automatically encompasses word boundaries. This will work with gawk or mawk
awk -v sUSER="$sUSER" '
!/^#/ {for (i=2; i<=NF; i++) if ($i == sUSER) print $1}
' /etc/hosts
answered Nov 21 '18 at 20:05
glenn jackmanglenn jackman
167k26147238
edited Nov 22 '18 at 18:24
answered Nov 21 '18 at 20:05
glenn jackmanglenn jackman
167k26147238
answered Nov 21 '18 at 20:05
glenn jackmanglenn jackman
167k26147238
answered Nov 21 '18 at 20:05
glenn jackmanglenn jackman
167k26147238
167k26147238
Whitespace is your friend. Indentation solves a lot of debugging, lol
– Paul Hodges
Nov 21 '18 at 20:54
Hi Glenn - I used this code and my symptoms are the same. I have actually tried using this "awk" statement on 5 different machines, 4 of them it did not work and one it did work. It worked on the one that it always worked on. Do you think maybe there is a missing library or something? Maybe I should try and reinstall awk/mawk/gawk ?? I am really becoming perplexed with this. I have checked syslog and it reports nothing.
– WesZ
Nov 22 '18 at 9:47
I did note that the word boundaries are a GNU awk feature. GNU awk is not installed by default on some distributions: what awk are you running? And awk errors will not be syslogged.
– glenn jackman
Nov 22 '18 at 14:06
Well... it seems "Houston.....we have a problem...." The one that works fine is GNU Awk 4.1.3, API: 1.1 (GNU MPFR 3.1.4, GNU MP 6.1.0) and the one that has problems is awk: not an option: --version awk -Wversion 2>/dev/null || awk --version mawk 1.3.3 Nov 1996, Copyright (C) Michael D. Brennan so what should I do?
– WesZ
Nov 22 '18 at 16:11
So is it gawk that needs to be installed to get the GNU stuff?
– WesZ
Nov 22 '18 at 16:18
|
show 2 more comments
Whitespace is your friend. Indentation solves a lot of debugging, lol
– Paul Hodges
Nov 21 '18 at 20:54
Hi Glenn - I used this code and my symptoms are the same. I have actually tried using this "awk" statement on 5 different machines, 4 of them it did not work and one it did work. It worked on the one that it always worked on. Do you think maybe there is a missing library or something? Maybe I should try and reinstall awk/mawk/gawk ?? I am really becoming perplexed with this. I have checked syslog and it reports nothing.
– WesZ
Nov 22 '18 at 9:47
I did note that the word boundaries are a GNU awk feature. GNU awk is not installed by default on some distributions: what awk are you running? And awk errors will not be syslogged.
– glenn jackman
Nov 22 '18 at 14:06
Well... it seems "Houston.....we have a problem...." The one that works fine is GNU Awk 4.1.3, API: 1.1 (GNU MPFR 3.1.4, GNU MP 6.1.0) and the one that has problems is awk: not an option: --version awk -Wversion 2>/dev/null || awk --version mawk 1.3.3 Nov 1996, Copyright (C) Michael D. Brennan so what should I do?
– WesZ
Nov 22 '18 at 16:11
So is it gawk that needs to be installed to get the GNU stuff?
– WesZ
Nov 22 '18 at 16:18
Whitespace is your friend. Indentation solves a lot of debugging, lol
– Paul Hodges
Nov 21 '18 at 20:54
Whitespace is your friend. Indentation solves a lot of debugging, lol
– Paul Hodges
Nov 21 '18 at 20:54
Hi Glenn - I used this code and my symptoms are the same. I have actually tried using this "awk" statement on 5 different machines, 4 of them it did not work and one it did work. It worked on the one that it always worked on. Do you think maybe there is a missing library or something? Maybe I should try and reinstall awk/mawk/gawk ?? I am really becoming perplexed with this. I have checked syslog and it reports nothing.
– WesZ
Nov 22 '18 at 9:47
Hi Glenn - I used this code and my symptoms are the same. I have actually tried using this "awk" statement on 5 different machines, 4 of them it did not work and one it did work. It worked on the one that it always worked on. Do you think maybe there is a missing library or something? Maybe I should try and reinstall awk/mawk/gawk ?? I am really becoming perplexed with this. I have checked syslog and it reports nothing.
– WesZ
Nov 22 '18 at 9:47
I did note that the word boundaries are a GNU awk feature. GNU awk is not installed by default on some distributions: what awk are you running? And awk errors will not be syslogged.
– glenn jackman
Nov 22 '18 at 14:06
I did note that the word boundaries are a GNU awk feature. GNU awk is not installed by default on some distributions: what awk are you running? And awk errors will not be syslogged.
– glenn jackman
Nov 22 '18 at 14:06
Well... it seems "Houston.....we have a problem...." The one that works fine is GNU Awk 4.1.3, API: 1.1 (GNU MPFR 3.1.4, GNU MP 6.1.0) and the one that has problems is awk: not an option: --version awk -Wversion 2>/dev/null || awk --version mawk 1.3.3 Nov 1996, Copyright (C) Michael D. Brennan so what should I do?
– WesZ
Nov 22 '18 at 16:11
Well... it seems "Houston.....we have a problem...." The one that works fine is GNU Awk 4.1.3, API: 1.1 (GNU MPFR 3.1.4, GNU MP 6.1.0) and the one that has problems is awk: not an option: --version awk -Wversion 2>/dev/null || awk --version mawk 1.3.3 Nov 1996, Copyright (C) Michael D. Brennan so what should I do?
– WesZ
Nov 22 '18 at 16:11
So is it gawk that needs to be installed to get the GNU stuff?
– WesZ
Nov 22 '18 at 16:18
So is it gawk that needs to be installed to get the GNU stuff?
– WesZ
Nov 22 '18 at 16:18
|
show 2 more comments
What you basically want to do is a local hostname lookup. There is a tool called getent for that purpose:
getent -s files hosts "${sUSER}" | cut -d' ' -f1
-s files tells getent to only use the local host databases (not DNS) which is /etc/hosts.
answered Nov 21 '18 at 17:53
hek2mglhek2mgl
108k13144166
Hello, this getent works, but can it be made to use a specified file? I looked on the man page, but it wasn't mentioned. I can use this, I would need to re-write some code to append the /etc/hosts file. If I can, I would like to use the awk code, although it is becoming a bit clunky... so maybe this is a better solution. Thanks.
– WesZ
Nov 21 '18 at 19:03
getent hostsis always using/etc/hosts. What you basically want to do is a local hostname lookup.getent -s filesis made for that.
– hek2mgl
Nov 21 '18 at 19:13
add a comment |
What you basically want to do is a local hostname lookup. There is a tool called getent for that purpose:
getent -s files hosts "${sUSER}" | cut -d' ' -f1
-s files tells getent to only use the local host databases (not DNS) which is /etc/hosts.
answered Nov 21 '18 at 17:53
hek2mglhek2mgl
108k13144166
Hello, this getent works, but can it be made to use a specified file? I looked on the man page, but it wasn't mentioned. I can use this, I would need to re-write some code to append the /etc/hosts file. If I can, I would like to use the awk code, although it is becoming a bit clunky... so maybe this is a better solution. Thanks.
– WesZ
Nov 21 '18 at 19:03
getent hostsis always using/etc/hosts. What you basically want to do is a local hostname lookup.getent -s filesis made for that.
– hek2mgl
Nov 21 '18 at 19:13
add a comment |
What you basically want to do is a local hostname lookup. There is a tool called getent for that purpose:
getent -s files hosts "${sUSER}" | cut -d' ' -f1
-s files tells getent to only use the local host databases (not DNS) which is /etc/hosts.
answered Nov 21 '18 at 17:53
hek2mglhek2mgl
108k13144166
What you basically want to do is a local hostname lookup. There is a tool called getent for that purpose:
getent -s files hosts "${sUSER}" | cut -d' ' -f1
-s files tells getent to only use the local host databases (not DNS) which is /etc/hosts.
answered Nov 21 '18 at 17:53
hek2mglhek2mgl
108k13144166
edited Nov 21 '18 at 19:17
answered Nov 21 '18 at 17:53
hek2mglhek2mgl
108k13144166
answered Nov 21 '18 at 17:53
hek2mglhek2mgl
108k13144166
answered Nov 21 '18 at 17:53
hek2mglhek2mgl
108k13144166
108k13144166
Hello, this getent works, but can it be made to use a specified file? I looked on the man page, but it wasn't mentioned. I can use this, I would need to re-write some code to append the /etc/hosts file. If I can, I would like to use the awk code, although it is becoming a bit clunky... so maybe this is a better solution. Thanks.
– WesZ
Nov 21 '18 at 19:03
getent hostsis always using/etc/hosts. What you basically want to do is a local hostname lookup.getent -s filesis made for that.
– hek2mgl
Nov 21 '18 at 19:13
add a comment |
Hello, this getent works, but can it be made to use a specified file? I looked on the man page, but it wasn't mentioned. I can use this, I would need to re-write some code to append the /etc/hosts file. If I can, I would like to use the awk code, although it is becoming a bit clunky... so maybe this is a better solution. Thanks.
– WesZ
Nov 21 '18 at 19:03
getent hostsis always using/etc/hosts. What you basically want to do is a local hostname lookup.getent -s filesis made for that.
– hek2mgl
Nov 21 '18 at 19:13
Hello, this getent works, but can it be made to use a specified file? I looked on the man page, but it wasn't mentioned. I can use this, I would need to re-write some code to append the /etc/hosts file. If I can, I would like to use the awk code, although it is becoming a bit clunky... so maybe this is a better solution. Thanks.
– WesZ
Nov 21 '18 at 19:03
Hello, this getent works, but can it be made to use a specified file? I looked on the man page, but it wasn't mentioned. I can use this, I would need to re-write some code to append the /etc/hosts file. If I can, I would like to use the awk code, although it is becoming a bit clunky... so maybe this is a better solution. Thanks.
– WesZ
Nov 21 '18 at 19:03
getent hosts is always using /etc/hosts. What you basically want to do is a local hostname lookup. getent -s files is made for that.– hek2mgl
Nov 21 '18 at 19:13
getent hosts is always using /etc/hosts. What you basically want to do is a local hostname lookup. getent -s files is made for that.– hek2mgl
Nov 21 '18 at 19:13
add a comment |
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What is the sample file you are running this on? Give us a proper reproducible example to help us solve your problem
– Inian
Nov 21 '18 at 17:26
Hello, the sample file is the /etc/hosts file as shown at the end of the awk statement and once again, as is stated, this awk looks into the /etc/hosts file and extracts an IP address for a given username/hostname.
– WesZ
Nov 21 '18 at 17:57
1
@WesZ, your previous thread stackoverflow.com/questions/53353494/… how different it is please do let us know? That thread also you have not informed anyone about what happened, so please don't do so, take questions/problems one by one only
– RavinderSingh13
Nov 21 '18 at 18:01
It says:Thanks. Hello. I wanted to post my final line of code that provides the correct output. I appreciate all of the help and guidance from those who responded. I wanted to post the final code in case someone in the future can find it useful.
– WesZ
Nov 21 '18 at 18:06
@WesZ, could you please do let us know if you have taken guidance from my or hek2mgl post. Both are based on different approaches but you should try it out both and let individual know about its status then/.
– RavinderSingh13
Nov 21 '18 at 18:08