Shell Scripting

Shell scripting is the process of writing lists of commands to be run as a macro from a computer's shell ( or Terminal). These can contain any executable function, as well as a few others, that you would normally run in a Terminal. Once completed these macros can be instructed to run automatically upon different system events or times to help you to automate your life.

Transcript

1. Shell Scripting
2. Why shell?
4. What is it?
5. .sh
7. chmod 777 script.sh
8. chmod 666 script.sh 666
9. chmod 755 script.sh
10. ./script.sh
11. bash script.sh
12. sh script.sh
14. Initialization
15. #!/bin/ Initialization bash sh csh zsh bash
16. #!/bin/ Initialization bash
17. #!/bin/bash dest_folder=$1 …
18. $./backup.sh ~/ /mnt/bac
19. $./backup.sh ~/ /mnt/bac $1 $2
20. $./backup.sh ~/ /mnt/bac $1 $2
21. $./backup.sh ~/ /mnt/bac $1 $2 $0
22. $echo $0
23. $echo $0 -bash
24. #!/bin/bash dest_folder=$1 backup_folder=$2 …
25. … #unique backup ID’s day=$(date “+%y%m%d”) host=$(hostname -s) …
26. … #archive file name archive=“$host-$day.tgz” …
27. … #print start message echo “$0: Backing up $backup_folder to $dest_folder…” date echo …
28. … #compress files using tar tar czvf “$dest_folder/$archive” $backup_folder …
29. … #print completion message echo echo “Backup complete!” echo ls -lh $dest_folder
31. Improvements
32. If Statement
33. #!/bin/bash #check for arguments if [[ $# -lt 2 ]] ; then echo "$0: illegal number of params" echo "usage: [dest folder] [backup dirs...]" exit 1 fi …
34. #!/bin/bash #check for arguments if [[ $# -lt 2 ]] ; then echo "$0: illegal number of params" echo "usage: [dest folder] [backup dirs...]" exit 1 fi …
35. #!/bin/bash #check for arguments if [[ $# -lt 2 ]] ; then echo "$0: illegal number of params" echo "usage: [dest folder] [backup dirs...]" exit 1 fi …
36. #!/bin/bash #check for arguments if [ “$#” -lt 2 ] ; then echo "$0: illegal number of params" echo "usage: [dest folder] [backup dirs...]" exit 1 fi …
37. #!/bin/bash #check for arguments if [[ $# -lt 2 ]] ; then echo "$0: illegal number of params" echo "usage: [dest folder] [backup dirs...]" exit 1 fi …
38. #!/bin/bash #check for arguments if [[ $# -lt 2 ]] then echo "$0: illegal number of params" echo "usage: [dest folder] [backup dirs...]" exit 1 fi …
39. #!/bin/bash #check for arguments if [[ $# -lt 2 ]] ; then echo "$0: number of params" echo "usage: [dest folder] [backup dirs...]" exit 1 fi …
40. #!/bin/bash test $# -lt 2 && (echo not enough arguments)
41. #!/bin/bash test $# -lt 2 && (echo not enough arguments)
42. #!/bin/bash test $# -lt 2 && (echo not enough arguments)
43. #!/bin/bash test $# -lt 2 | | (echo valid num of arguments)
44. #!/bin/bash #check for arguments if [[ $# -lt 2 ]] ; then echo "$0: illegal number of params" echo "usage: [dest folder] [backup dirs...]" exit 1 fi …
46. For Loop
47. … create_backup () { #archive file name archive="$host-$day-$1.tgz" #print start message echo echo "Backing up $1 to $dest_folder/$archive” echo #compress files using tar tar czvf "$dest_folder/$archive" "$1" } …
48. … create_backup () { #archive file name archive="$host-$day-$1.tgz" #print start message echo echo "Backing up $1 to $dest_folder/$archive” echo #compress files using tar tar czvf "$dest_folder/$archive" "$1" } …
49. … count=0 for folder in "$@"; do test $count -eq 0 | | (create_backup $folder) count+=1 done …
50. … count=0 for folder in "$@"; do test $count -eq 0 | | (create_backup $folder) count+=1 done …
51. … count=0 for folder in “$@" do test $count -eq 0 | | (create_backup $folder) count+=1 done …
52. … count=0 for folder in "$@"; do test $count -eq 0 | | (create_backup $folder) count+=1 done …
53. … count=0 for folder in "$@"; do test $count -eq 0 | | (create_backup $folder) count+=1 done …
54. … count=0 for folder in "$@"; do test $count -eq 0 | | (create_backup $folder) count+=1 done …
56. Control Structure Other
57. While loop
58. count=0 while [[ $count -lt 10 ]]; do echo “count = $count” done
59. cases
60. time=$(date “+%H”) case $time in [6-10]) echo “morning”;; [11-5]) echo “day”;; [6-10]) echo “evening”;; *) echo “night”;; esac
61. Thanks! Jason Merlo