diff --git a/sources/tech/20170614 Automatically Create Remove And Mount Swap File In Linux Using Shell Script.md b/sources/tech/20170614 Automatically Create Remove And Mount Swap File In Linux Using Shell Script.md new file mode 100644 index 0000000000..7d8159c1c4 --- /dev/null +++ b/sources/tech/20170614 Automatically Create Remove And Mount Swap File In Linux Using Shell Script.md @@ -0,0 +1,150 @@ +Automatically Create/Remove And Mount Swap File In Linux Using Shell Script +============================================================  + + +Few days ago we have covered an article about swap file creation in Linux using three ways which is the common method but it requires manual human effort. + +Today i have found a small shell script (Two shell script, one for swap file creation and another one for removing swap file) which was written by [Gary Stafford][3] that help us to create/remove & mount swap file automatically in Linux. + +By default the script create and mount `512MB` swapfile. If you want more swap space and different file name you have to modify the script accordingly. It’s not a big deal to modify the script since it’s very handy and small script, even though i have colored the line where you want to modify the script. + +**Suggested Read : **[3 Easy Ways To Create Or Extend Swap Space In Linux][4] + +#### How to check current swap size + +Lets first check the size of existing swap space partition using **[free][1]** & `swapon` command. + +``` +$ free -h + total used free shared buff/cache available +Mem: 2.0G 1.3G 139M 45M 483M 426M +Swap: 2.0G 655M 1.4G + +$ swapon --show +NAME TYPE SIZE USED PRIO +/dev/sda5 partition 2G 655.2M -1 +``` + +The above output clearly shows `2GB` is my current swap space. + +#### Create Swap File + +Create `create_swap.sh` file and add below script to automate the swap space creation and mounting. + +``` +$ nano create_swap.sh +#!/bin/sh + +# size of swapfile in megabytes +swapsize=1024 + +# does the swap file already exist? +grep -q "swapfile" /etc/fstab + +# if not then create it +if [ $? -ne 0 ]; then + echo 'swapfile not found. Adding swapfile.' + fallocate -l ${swapsize}M /swapfile + chmod 600 /swapfile + mkswap /swapfile + swapon /swapfile + echo '/swapfile none swap defaults 0 0' >> /etc/fstab +else + echo 'swapfile found. No changes made.' +fi + +echo '--------------------------------------------' +echo 'Check whether the swap space created or not?' +echo '--------------------------------------------' +swapon --show +``` + +Add execute permission to the file. + +``` +$ sudo +x create_swap.sh +``` + +Run the file to create and mount swap file. + +``` +$ sudo ./create_swap.sh + +swapfile not found. Adding swapfile. +Setting up swapspace version 1, size = 1024 MiB (1073737728 bytes) +no label, UUID=d9004261-396a-4321-a45f-9923e3e1328c +-------------------------------------------- +Check whether the swap space created or not? +-------------------------------------------- +NAME TYPE SIZE USED PRIO +/dev/sda5 partition 2G 954.1M -1 +/swapfile file 1024M 0B -2 +``` + +Yes i can see the new `1024M swapfile`. Reboot the system to use the new swap file. + +#### Remove Swap File + +If the swap file is no longer required, then create `remove_swap.sh` file and add below script to remove swap file and its mount point from /etc/fstab. + +``` +$ nano remove_swap.sh +#!/bin/sh + +# does the swap file exist? +grep -q "swapfile" /etc/fstab + +# if it does then remove it +if [ $? -eq 0 ]; then + echo 'swapfile found. Removing swapfile.' + sed -i '/swapfile/d' /etc/fstab + echo "3" > /proc/sys/vm/drop_caches + swapoff -a + rm -f /swapfile +else + echo 'No swapfile found. No changes made.' +fi + +echo '--------------------------------------------' +echo 'Check whether the swap space removed or not?' +echo '--------------------------------------------' +swapon --show +``` + +Add execute permission to the file. + +``` +$ sudo +x remove_swap.sh +``` + +Run the file to remve and unmount swap file. + +``` +$ sudo ./remove_swap.sh + +swapfile found. Removing swapfile. +swapoff: /dev/sda5: swapoff failed: Cannot allocate memory +-------------------------------------------- +Check whether the swap space removed or not? +-------------------------------------------- +NAME TYPE SIZE USED PRIO +/dev/sda5 partition 2G 951.8M -1 +``` + + + +-------------------------------------------------------------------------------- + +via: http://www.2daygeek.com/shell-script-create-add-extend-swap-space-linux/ + +作者：[2DAYGEEK ][a] +译者：[译者ID](https://github.com/译者ID) +校对：[校对者ID](https://github.com/校对者ID) + +本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出 + +[a]:http://www.2daygeek.com/author/2daygeek/ +[1]:http://www.2daygeek.com/free-command-to-check-memory-usage-statistics-in-linux/ +[2]:http://www.2daygeek.com/author/2daygeek/ +[3]:https://programmaticponderings.com/2013/12/19/scripting-linux-swap-space/ +[4]:http://www.2daygeek.com/add-extend-increase-swap-space-memory-file-partition-linux/