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authorHeinrich Schuchardt2021-01-20 18:09:30 +0100
committerHeinrich Schuchardt2021-01-25 01:15:33 +0100
commitde702493c449200a0e84c8e6dcc58deb49837691 (patch)
treed191a792cab9daeff58f022629d35e277d9ee7ac /doc/usage
parent627b57bde05063b2f512d8e3ec6f8060aea25b91 (diff)
doc: document for statement
Create a man-page for the for statement. Signed-off-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
Diffstat (limited to 'doc/usage')
-rw-r--r--doc/usage/for.rst65
-rw-r--r--doc/usage/index.rst1
2 files changed, 66 insertions, 0 deletions
diff --git a/doc/usage/for.rst b/doc/usage/for.rst
new file mode 100644
index 00000000000..f9e504979c3
--- /dev/null
+++ b/doc/usage/for.rst
@@ -0,0 +1,65 @@
+for command
+===========
+
+Synopis
+-------
+
+::
+
+ for <variable> in <items>; do <commands>; done
+
+Description
+-----------
+
+The for command is used to loop over a list of values and execute a series of
+commands for each of these.
+
+The counter variable of the loop is a shell variable. Please, keep in mind that
+an environment variable takes precedence over a shell variable of the same name.
+
+variable
+ name of the counter variable
+
+items
+ space separated item list
+
+commands
+ commands to execute
+
+Example
+-------
+
+::
+
+ => setenv c
+ => for c in 1 2 3; do echo item ${c}; done
+ item 1
+ item 2
+ item 3
+ => echo ${c}
+ 3
+ => setenv c x
+ => for c in 1 2 3; do echo item ${c}; done
+ item x
+ item x
+ item x
+ =>
+
+The first line ensures that there is no environment variable *c*. Hence in the
+first loop the shell variable *c* is printed.
+
+After defining an environment variable of name *c* it takes precedence over the
+shell variable and the environment variable is printed.
+
+Return value
+------------
+
+The return value $? after the done statement is the return value of the last
+statement executed in the loop.
+
+::
+
+ => for i in true false; do ${i}; done; echo $?
+ 1
+ => for i in false true; do ${i}; done; echo $?
+ 0
diff --git a/doc/usage/index.rst b/doc/usage/index.rst
index b8f216b7132..6f49652758f 100644
--- a/doc/usage/index.rst
+++ b/doc/usage/index.rst
@@ -18,6 +18,7 @@ Shell commands
bootmenu
button
exit
+ for
mbr
pstore
sbi