I want to write the Ubuntu analogue of a "batch file" (a shell script). But I don't know how to use
chmod +x filename command to make it so that the script can be run. Nor do I know where to use it.
chmod +x on a file (your script) only means, that you'll make it executable. Right click on your script and chose Properties -> Permissions -> Allow executing file as program, leaves you with the exact same result as the command in terminal.
If a file you want to change permissions on is located within the systems directory you may need to be
root, like so: (be careful, while using
sudo chmod +x /usr/share/testfolder/aFile
Also it is not clear, what exactly you want to archive here. Please edit your question and give some more detail on the actual problem!
You can also refer to this question, for more information: chmod u+x' versus 'chmod +x
man chmod in a terminal window (Ctrl+Alt+T) and you'll get the following output:
NAME: chmod - change file mode bits
chmod [OPTION]... MODE[,MODE]... FILE... chmod [OPTION]... OCTAL-MODE FILE... chmod [OPTION]... --reference=RFILE FILE...
This manual page documents the GNU version of chmod. chmod changes the file mode bits of each given file according to mode, which can be either a symbolic representation of changes to make, or an octal number repre‐ senting the bit pattern for the new mode bits. The format of a symbolic mode is [ugoa...][[+-=][perms...]...], where perms is either zero or more letters from the set rwxXst, or a single letter from the set ugo. Multiple symbolic modes can be given, sepa‐ rated by commas. A combination of the letters ugoa controls which users' access to the file will be changed: the user who owns it (u), other users in the file's group (g), other users not in the file's group (o), or all users (a). If none of these are given, the effect is as if a were given, but bits that are set in the umask are not affected. The operator + causes the selected file mode bits to be added to the existing file mode bits of each file; - causes them to be removed; and = causes them to be added and causes unmentioned bits to be removed except that a directory's unmentioned set user and group ID bits are not affected. The letters rwxXst select file mode bits for the affected users: read (r), write (w), execute (or search for directories) (x), execute/search only if the file is a directory or already has execute permission for some user (X), set user or group ID on execution (s), restricted dele‐ tion flag or sticky bit (t). Instead of one or more of these letters, you can specify exactly one of the letters ugo: the permissions granted to the user who owns the file (u), the permissions granted to other users who are members of the file's group (g), and the permissions granted to users that are in neither of the two preceding categories (o). A numeric mode is from one to four octal digits (0-7), derived by adding up the bits with values 4, 2, and 1. Omitted digits are assumed to be leading zeros. The first digit selects the set user ID (4) and set group ID (2) and restricted deletion or sticky (1) attributes. The sec‐ ond digit selects permissions for the user who owns the file: read (4), write (2), and execute (1); the third selects permissions for other users in the file's group, with the same values; and the fourth for other users not in the file's group, with the same values. chmod never changes the permissions of symbolic links; the chmod system call cannot change their permissions. This is not a problem since the permissions of symbolic links are never used. However, for each sym‐ bolic link listed on the command line, chmod changes the permissions of the pointed-to file. In contrast, chmod ignores symbolic links encoun‐ tered during recursive directory traversals.
SETUID AND SETGID BITS
chmod clears the set-group-ID bit of a regular file if the file's group ID does not match the user's effective group ID or one of the user's supplementary group IDs, unless the user has appropriate privileges. Additional restrictions may cause the set-user-ID and set-group-ID bits of MODE or RFILE to be ignored. This behavior depends on the policy and functionality of the underlying chmod system call. When in doubt, check the underlying system behavior.
Change the mode of each FILE to MODE. -c, --changes like verbose but report only when a change is made --no-preserve-root do not treat `/' specially (the default) --preserve-root fail to operate recursively on `/' -f, --silent, --quiet suppress most error messages -v, --verbose output a diagnostic for every file processed --reference=RFILE use RFILE's mode instead of MODE values -R, --recursive change files and directories recursively --help display this help and exit --version output version information and exit Each MODE is of the form `[ugoa]*([-+=]([rwxXst]*|[ugo]))+'.
First, your script must declare which interpreter to use. You do this in the first line of the file. If it's a shell script, it should be
So here's a script that writes your username: echo-whoami.sh
To make it executable, use
chmod +x echo-whoami.sh. Then you can run it using
A batch file and a shell script are two terms meaning effectively the same under Linux. The term script is far more often used, though.
The most simple shell script file just contains commands as you'd type them on the command line (that is, the Bash command interpreter). In theory you can even replace the interpreter with any language you like (and have an interpreter for). To be more explicit, it's suggested you start your first line with
#!/bin/sh (if you wan't maximum portability with legacy systems)
#!/bin/bash (if you want some extra features, you probably don't care about today)
After this line enter your commands, one on each line. There are lots of extra constructs beyond the scope of this questions, see
man bash or http://www.tldp.org/LDP/Bash-Beginners-Guide/Bash-Beginners-Guide.pdf (for Beginners) or http://www.tldp.org/LDP/abs/abs-guide.pdf (for more advanced questions).
To actually run your script, there are two requirements: First, the interpreter process needs to read the file, and second it checks if it is marked as executable. For convenience reasons it's also useful to be able to write to your script (so you can make changes or fixes should need be).
Assuming further that you want team members and other also to be able to run (and see) your script, but that you don't want them to manipulate it, the combination of
- execute rights for all (
ais the default),
- read rights for all (
ais again the default),
- write permissions just for you (
are usually sensible values of your file permissions. You can type the single actions concatenated, separated with a comma.
While this "action language" is very fascinating (note the difference of the
+ and the
= operator which result in different outcomes depending of the permission setting before you changed them), they are tedious to type.
As all of the actions create bit masks that are applied internally, you can type the bitmasks (see
man chmod for details) also directly.
For a shellscript chmod 755 myscript.sh makes most sense in at least 95% of all cases.