How to replace string in a file

Question

I am writing shell script which will list the drivers .ko files and adding entry in init file. File comes in initramfs.

so below some thing i have did in script, I tried google but solutions not working so finally i had to post question.

few issues,

1) i was trying to store strings with newline character in a variable, but it makes it in a single line, so i used different approach i written a file which has data as expected.

2) Now i want the content with new line chars to be placed in middle of init file, which is below some driver entry so i decided to find last driver, then replace my content with driver and then again append that driver back in file.

3)But i am not able to replace text so i used again different approach to write new file line by line and when i will find driver add my content and append driver back in file. But now content i saved in earlier file appended in a single line no newline character it.

I am not an expert in shell i am doing all it with google. below is my code

    #!/bin/bash
    rm tmp.txt
    handled_drivers=()
    for driver in `cat lib/modules/2.6.18-419.el5/modules.dep | tr -d ":" | tr " " "\n"`
    do
            handled=0
            for d in ${handled_drivers[@]}
            do
                    if [ "$d" == "$driver" ]
                    then
                       handled=1
                    fi
            done
            if [ $handled -eq 0 ]
            then
                 handled_drivers+=($driver)
                 echo "insmod $driver" >> tmp.txt
                 echo "echo \"Loading $(basename "$driver") module\"" >> tmp.txt
            fi
    done

    value=`cat tmp.txt`

    find_last_driver=`cat initcopy | grep insmod | tail -1| tr -d "\n"`

    #
    #if [[ -z $find_last_driver ]];then
    #   echo "Not Found driver skip injection"
    #else
    #   echo "here $find_last_driver"
    #   sed -i -e 's/$find_last_driver/$value/g' ./a.txt
    #fi

    while IFS= read -r line;do
        if [ "$line" == "$find_last_driver" ]
        then
        echo $value >>  init_new
        echo $line >> init_new
    else
        echo $line >> init_new
    fi
done < "init"

Below is content of the output file:

#!/bin/nash

mount -t proc /proc /proc
setquiet
echo Mounting proc filesystem
echo Mounting sysfs filesystem
mount -t sysfs /sys /sys
echo Creating /dev
mount -o mode=0755 -t tmpfs /dev /dev
mkdir /dev/pts
mount -t devpts -o gid=5,mode=620 /dev/pts /dev/pts
mkdir /dev/shm
mkdir /dev/mapper
echo Setting up hotplug.
hotplug
insmod /lib/uhci-hcd.ko
mount -t usbfs /proc/bus/usb /proc/bus/usb
echo "Loading jbd.ko module"
insmod /lib/jbd.ko
echo "Loading ext3.ko module"
insmod /lib/ext3.ko
echo "Loading scsi_mod.ko module"
insmod /lib/dm-message.ko
echo "Loading dm-raid45.ko module"
insmod /lib/modules/2.6.18-419.el5/kernel/drivers/ata/ata_piix.ko echo "Loading ata_piix.ko module" insmod /lib/modules/2.6.18-419.el5/kernel/drivers/ata/libata.ko echo "Loading libata.ko module" insmod /lib/modules/2.6.18-419.el5/kernel/drivers/scsi/scsi_mod.ko echo "Loading scsi_mod.ko module" insmod /lib/modules/2.6.18-419.el5/kernel/crypto/crypto_algapi.ko echo "Loading crypto_algapi.ko module" insmod /lib/modules/2.6.18-419.el5/kernel/crypto/crypto_api.ko echo "Loading crypto_api.ko module" insmod /lib/modules/2.6.18-419.el5/kernel/drivers/md/dm-crypt.ko echo "Loading dm-crypt.ko module" insmod /lib/modules/2.6.18-419.el5/kernel/drivers/md/dm-mod.ko echo "Loading dm-mod.ko module" insmod /lib/modules/2.6.18-419.el5/kernel/drivers/md/dm-emc.ko echo "Loading dm-emc.ko module" insmod /lib/modules/2.6.18-419.el5/kernel/drivers/md/dm-multipath.ko echo "Loading dm-multipath.ko module" insmod /lib/modules/2.6.18-419.el5/kernel/drivers/scsi/device_handler/scsi_dh.ko echo "Loading scsi_dh.ko module" insmod /lib/modules/2.6.18-419.el5/kernel/drivers/md/dm-hp-sw.ko echo "Loading dm-hp-sw.ko module" insmod /lib/modules/2.6.18-419.el5/kernel/drivers/md/dm-log.ko echo "Loading dm-log.ko module" insmod /lib/modules/2.6.18-419.el5/kernel/drivers/md/dm-mem-cache.ko echo "Loading dm-mem-cache.ko module" insmod /lib/modules/2.6.18-419.el5/kernel/drivers/md/dm-message.ko echo "Loading dm-message.ko module" insmod /lib/modules/2.6.18-419.el5/kernel/drivers/md/dm-mirror.ko echo "Loading dm-mirror.ko module" insmod /lib/modules/2.6.18-419.el5/kernel/drivers/md/dm-raid45.ko echo "Loading dm-raid45.ko module" insmod /lib/modules/2.6.18-419.el5/kernel/drivers/md/dm-region_hash.ko echo "Loading dm-region_hash.ko module" insmod /lib/modules/2.6.18-419.el5/kernel/drivers/md/dm-rdac.ko echo "Loading dm-rdac.ko module" insmod /lib/modules/2.6.18-419.el5/kernel/drivers/md/dm-round-robin.ko echo "Loading dm-round-robin.ko module" insmod /lib/modules/2.6.18-419.el5/kernel/drivers/md/dm-snapshot.ko echo "Loading dm-snapshot.ko module" insmod /lib/modules/2.6.18-419.el5/kernel/drivers/md/dm-zero.ko echo "Loading dm-zero.ko module" insmod /lib/modules/2.6.18-419.el5/kernel/drivers/usb/net/dm9601.ko echo "Loading dm9601.ko module" insmod /lib/modules/2.6.18-419.el5/kernel/drivers/usb/net/usbnet.ko echo "Loading usbnet.ko module" insmod /lib/modules/2.6.18-419.el5/kernel/drivers/dma/dmaengine.ko echo "Loading dmaengine.ko module" insmod /lib/modules/2.6.18-419.el5/kernel/drivers/hwmon/dme1737.ko echo "Loading dme1737.ko module" insmod /lib/modules/2.6.18-419.el5/kernel/drivers/i2c/i2c-core.ko echo "Loading i2c-core.ko module" insmod /lib/modules/2.6.18-419.el5/kernel/drivers/net/tulip/dmfe.ko echo "Loading dmfe.ko module" insmod /lib/modules/2.6.18-419.el5/kernel/drivers/scsi/mpt2sas/mpt2sas.ko echo "Loading mpt2sas.ko module" insmod /lib/modules/2.6.18-419.el5/kernel/drivers/scsi/scsi_transport_sas.ko echo "Loading scsi_transport_sas.ko module" insmod /lib/modules/2.6.18-419.el5/kernel/drivers/message/fusion/mptbase.ko echo "Loading mptbase.ko module" insmod /lib/modules/2.6.18-419.el5/kernel/drivers/message/fusion/mptctl.ko echo "Loading mptctl.ko module" insmod /lib/modules/2.6.18-419.el5/kernel/drivers/message/fusion/mptfc.ko echo "Loading mptfc.ko module" insmod /lib/modules/2.6.18-419.el5/kernel/drivers/message/fusion/mptscsih.ko echo "Loading mptscsih.ko module" insmod /lib/modules/2.6.18-419.el5/kernel/drivers/message/fusion/mptlan.ko echo "Loading mptlan.ko module" insmod /lib/modules/2.6.18-419.el5/kernel/drivers/message/fusion/mptsas.ko echo "Loading mptsas.ko module" insmod /lib/modules/2.6.18-419.el5/kernel/drivers/message/fusion/mptspi.ko echo "Loading mptspi.ko module" insmod /lib/modules/2.6.18-419.el5/misc/pvscsi.ko echo "Loading pvscsi.ko module" insmod /lib/modules/2.6.18-419.el5/kernel/drivers/scsi/device_handler/scsi_dh_alua.ko echo "Loading scsi_dh_alua.ko module" insmod /lib/modules/2.6.18-419.el5/kernel/drivers/scsi/device_handler/scsi_dh_emc.ko echo "Loading scsi_dh_emc.ko module" insmod /lib/modules/2.6.18-419.el5/kernel/drivers/scsi/device_handler/scsi_dh_rdac.ko echo "Loading scsi_dh_rdac.ko module" insmod /lib/modules/2.6.18-419.el5/kernel/drivers/pci/hotplug/shpchp.ko echo "Loading shpchp.ko module" 
insmod /lib/dm-raid45.ko
echo Waiting for driver initialization.
stabilized --hash --interval 1000 /proc/scsi/scsi
mkblkdevs
echo Mounting root filesystem.
mount /sysroot
echo Setting up other filesystems.
setuproot
echo Switching to new root and running init.
switchroot

Answer 1

1) i was trying to store strings with newline character in a variable, but it makes it in a single line, so i used different approach i written a file which has data as expected.

when a variable contains spaces tabs newline to avoid splitting : surround with double quotes

    echo "$value" >>  init_new
    echo "$line" >> init_new

instead of

    echo $value >>  init_new
    echo $line >> init_new