if construct questionThis is a discussion on if construct question within the awk forums in Programming Languages category; Hello, I'm trying to write a script to edit the gdm.conf file in order to change the Welcome= line. I was trying: if ( $0~/^Welcome/) {print "Welcome=New welcome message"} which works, but I can't quite seem to get the correct syntax to say if there isn't a "^Welcome=" line, add one. Any suggestions? Thanks! Brad... | ||||||||
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#1
08-11-2008, 02:36 PM
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 if construct question Hello, I'm trying to write a script to edit the gdm.conf file in order to change the Welcome= line. I was trying: if ( $0~/^Welcome/) {print "Welcome=New welcome message"} which works, but I can't quite seem to get the correct syntax to say if there isn't a "^Welcome=" line, add one. Any suggestions? Thanks! Brad  |
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#2
08-11-2008, 02:59 PM
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| Re: if construct question brad.vanorden@gmail.com wrote: > Hello, > > I'm trying to write a script to edit the gdm.conf file in order to > change the Welcome= line. I was trying: > > if ( $0~/^Welcome/) {print "Welcome=New welcome message"} > > which works, but I can't quite seem to get the correct syntax to say > if there isn't a "^Welcome=" line, add one. Any suggestions? > I guess your working code is somewhere from the middle of a rule. A simple solution for adding a line at the end would be: .... if ( $0~/^Welcome/) {print "Welcome=New welcome message" ; seen=1} .... END {if (! seen) print "Welcome=New welcome message"} Hermann |
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#3
08-11-2008, 02:59 PM
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| Re: if construct question On Aug 11, 2:36 pm, brad.vanor...@gmail.com wrote: > Hello, > > I'm trying to write a script to edit the gdm.conf file in order to > change the Welcome= line. I was trying: > > if ( $0~/^Welcome/) {print "Welcome=New welcome message"} > > which works, but I can't quite seem to get the correct syntax to say > if there isn't a "^Welcome=" line, add one. Any suggestions? > > Thanks! > > Brad Came up with the answer. In the BEGIN section, set a variable to 0. If the pattern matches, change it to 1. In the END section, test if variable is 0. If so, print the new welcome message. Regards, Brad |
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#4
08-11-2008, 03:04 PM
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| Re: if construct question brad.vanorden@gmail.com wrote: > In the BEGIN section, set a variable to 0. You can just skip this part. Awk does it for you. Hermann |
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#5
08-11-2008, 09:03 PM
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| Re: if construct question In article <7635edff-946e-4749-9d91-91253030932c@w7g2000hsa.googlegroups.com> , brad.vanorden@gmail.com wrote: > Hello, > > I'm trying to write a script to edit the gdm.conf file in order to > change the Welcome= line. I was trying: > > if ( $0~/^Welcome/) {print "Welcome=New welcome message"} > > which works, but I can't quite seem to get the correct syntax to say > if there isn't a "^Welcome=" line, add one. Any suggestions? > > Thanks! > > Brad awk ' BEGIN { print "Welcome=New welcome message" } ! /^Welcome=/ { print } # print anything expect a welcome ' gdm.conf >new.gdm.conf |
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#6
08-11-2008, 10:47 PM
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| Re: if construct question On 8/11/2008 1:36 PM, brad.vanorden@gmail.com wrote: > Hello, > > I'm trying to write a script to edit the gdm.conf file in order to > change the Welcome= line. I was trying: > > if ( $0~/^Welcome/) {print "Welcome=New welcome message"} > > which works, but I can't quite seem to get the correct syntax to say > if there isn't a "^Welcome=" line, add one. Any suggestions? > > Thanks! > > Brad awk 'BEGIN{print "Welcome=New welcome message"} /^Welcome/{next}' file Ed. |
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