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author | 2023-10-10 14:33:42 +0000 | |
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committer | 2023-10-10 14:33:42 +0000 | |
commit | af1a266670d040d2f4083ff309d732d648afba2a (patch) | |
tree | 2fc46203448ddcc6f81546d379abfaeb323575e9 /roms/u-boot/doc/usage/for.rst | |
parent | e02cda008591317b1625707ff8e115a4841aa889 (diff) |
Change-Id: Iaf8d18082d3991dec7c0ebbea540f092188eb4ec
Diffstat (limited to 'roms/u-boot/doc/usage/for.rst')
-rw-r--r-- | roms/u-boot/doc/usage/for.rst | 65 |
1 files changed, 65 insertions, 0 deletions
diff --git a/roms/u-boot/doc/usage/for.rst b/roms/u-boot/doc/usage/for.rst new file mode 100644 index 000000000..f9e504979 --- /dev/null +++ b/roms/u-boot/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 |