Vrftjkry

We use the following script:

more test.sh

#!/bin/bash



while read -r line

do



echo $line



done < /tmp/file

This is the file:

kafka-broker,log.retention.hours,12

kafka-broker,default.replication.factor,2

fefolp-defaults,fefolp.history.fs.cleaner.interval,1d

fefolp-defaults,fefolp.history.fs.cleaner.maxAge,2d

fefolp-env,fefolp_daemon_memory,10000

blo-site,blo.nodemanager.localizer.cache.target-size-mb,10240

blo-site,blo.nodemanager.localizer.cache.cleanup.interval-ms,300000

ams-env,metrics_collector_heapsize,512

fefolp,hbase_master_heapsize,1408

fefolp,hbase_regionserver_heapsize,512

fefolp,hbase_master_xmn_size,192

core-site,blolp.proxyuser.ambari.hosts,*

core-site,Hadoop.proxyuser.root.groups,*

core-site,Hadoop.proxyuser.root.hosts,*

blo-site,blo.scheduler.minimum-allocation-mb,1024

blolp-env,fefolp_heapsize,4096

Remark - after the last line - there are no space!

But the script prints only these lines (except the last line):

./test.sh

kafka-broker,log.retention.hours,12

kafka-broker,default.replication.factor,2

fefolp-defaults,fefolp.history.fs.cleaner.interval,1d

fefolp-defaults,fefolp.history.fs.cleaner.maxAge,2d

fefolp-env,fefolp_daemon_memory,10000

blo-site,blo.nodemanager.localizer.cache.target-size-mb,140

blo-site,blo.nodemanager.localizer.cache.cleanup.interval-ms,300

ams-env,metrics_collector_heapsize,51

fefolp,hbase_master_heapsize,1408

fefolp,hbase_regionserver_heapsize,542

fefolp,hbase_master_xmn_size,19

core-site,blolp.proxyuser.ambari.hosts,*

core-site,Hadoop.proxyuser.root.groups,*

core-site,Hadoop.proxyuser.root.hosts,*

blo-site,blo.scheduler.minimum-allocation-mb,1024

Why does this happen?

Your input text contains an incomplete line as its last line. The last line is not terminated by a newline.

while IFS= read -r line || [ -n "$line" ]; do

    printf '%sn' "$line"

done <file

The above loop will read unmodified lines (without stripping whitespaces or interpreting backslashed control sequences) from the file called file and print them to standard output.

When an incomplete line is read, read will fail, but $line will still contain data. The extra -n test will detect this so that the loop body is allowed to output the incomplete line. In the iteration after that, read will fail again and $line will be an empty string, thus terminating the loop.